welcome to bbc news — i'm lewis vaughanjones. our top stories: a police officer dies after being rammed by a car outside the us capitol building in washington — another officer is being treated in hospital. the suspect who emerged from the car with a knife and ran at officers was shot — and died in hospital. the top homicide investigator for the us city of minneapolis gives evidence on day five of the trial into the alleged murder of george floyd. and — the big bang — new research suggests the asteroid that killed off the dinosaurs may have helped create the rainforests.

welcome to our viewers on pbs in america and around the globe. a police officer has died and another is in hospital after an attack on the us capitol. a man carrying a knife rammed a car into a barricade, before he was shot dead by police. president biden said he was heartbroken over the death of the officer. it's the second time the capitol has been targeted this year, after supporters of donald trump stormed the building in january. here's our north america editorjon sopel. sirens wail. we've been here before. lunchtime on a cold easter day and another emergency sirens wail. a man in a blue car rams two us capitol police officers near a barrier. as he gets out of his vehicle,

knife in hand, he's shot and has now died. immediately, congress goes into lockdown. a helicopter�*s summoned and lands in front of the capitol building. and the national guard, which has been on duty since the capitol riots ofjanuary 6, is mobilised. another terrifying moment for those who work in the congressional offices. at a hastily organised news conference, confirmation that one of the police officers has died as well. and it is with a very, very heavy heart that i announce one of our officers has succumbed to his injuries. but the assailant doesn't seem to have been on anyone�*s radar screens, and police are saying there doesn't seem to be an ongoing threat. it does not appear that he is known to the capitol police or the metropolitan police department at this time. crosstalk. sir? is this a terrorism—related incident? _ it does not appear to be terrorism—related, but obviously, we'll continue

to investigate to see if there's some type of nexus along those lines. it was only a few days ago that some of the intense security around the capitol, following january's shocking assault, was eased. just a week ago, the driver wouldn't have been able to get as close to the building as he did. what's happened today may be totally unrelated to the events of january 6, but there's a terrible sense of deja vu, a further heightening of the feeling of vulnerability. and once again, above america's august and imposing capitol building, flags have been ordered to fly at half—staff. jon sopel, bbc news, at the capitol. barbara plett usher, our us state department correspondent is outside the us capitol. over the past weeks, i think the city had begun to relax a bit more because since january 6, there'd been a massive security increase around the capitol building, as you know. there had been some warnings

about possible attacks, but nothing had happened. and now something has, so people are on edge again and nervous about what to expect. now, this is nothing like on the scale, of course, of what happened onjanuary 6 — which was a mob storming the capitol building with arms, hunting down congresspeople, attacking police officers. this is — seems to be a one—man attack. at this point, it appears that he acted alone. it's also not at all clear that he might be, you know, connected to some kind of political or other cause. the officers who spoke to us earlier said that they were not calling it a terrorist attack and this man has not appeared on law enforcement radar before, he's not known to police, so it's not clear what his motivation was. that will obviously be a big part of the investigation but, yes, it has rattled people to come three months

afterjanuary 6, and some of the congressional aides that the bbc spoke to said that did make them nervous, especially with the security around, that another attack could happen. we can now speak to former fbi special agent thomas o'connor, for over two decades he worked on thejoint terrorism task force in the washington field office. he joins us from virginia. thank you for coming on the programme. element thank you for having me and firstly i want to say the hearts —— our hearts go out to the family and officers from the us capitol police and family of officer billy evans. an awful day here in washington, dc. it highlights yet again unfortunately the dangers faced by officers in the capital. it by officers in the capital. it by officers in the capital. it certainly does and it shows that the threat continues, whatever that threat may be from, and as your correspondence said, that is something that the joint terrorism task force which

includes the us capitol police, the metropolitan police and the fbi, will be delving into and describing all social media, and anything related to the subject who was killed on the scene today after this attack. it may turn out that there is an ideological backing to this. it may turn out that mental illness was a combination —— with a combination, may have been what led to this incident. this capital, much like westminster in the uk, is a target, and the officers who work at the us capitol every day put their lives on the line to protect their building and the people who are in it and they should be complemented for they should be complemented for the job they they should be complemented for thejob they did. they should be complemented for the job they did. this was not a breach of security, this is what the security does. it stopped the vehicle from getting in, those officers did theirjob and sadly one was killed and one was injured. fin killed and one was in'ured. on the killed and one was injured. on the possible search now for motives which is clearly in the

minds of so many people. what kind of areas will people be looking at, the investigating officers. what are the other avenues they will be exploring? social media in this day and age really does shine a light into the mindset of the person thatis into the mindset of the person that is being investigated, but along with that there will be search warrants that are served at this person's residence. the vehicle is being searched. all of these things come together, and there may be some fringe ideology, it is being reported a follower of the nation of islam which is anti—semitic, more of a racially motivated group, but that doesn't digitally have to be the reason the person did it, it could be mental illness that was spurred on by that conspiracy —— by

conspiracy theories and other ideologies. we see a lot more of mental illness playing into the groups that were involved in the capital takeover, many of those people have the same type of issues. the pandemic, the lockdown, being kept on the computer mostly 2a hours a day. we are having these issues are springing up, i would say around the globe, actually. evenif around the globe, actually. even if you think that is the kind of trend now. what do you make of the policing and security around the capital? do you think the extended barricades and increased presence is here to stay? some people are saying it has recently been scaled back a little, in the last week even. how do you view it, notjust in the weeks and months ahead now but years ahead.— but years ahead. security officials are _ but years ahead. security officials are going - but years ahead. security | officials are going to have but years ahead. security i officials are going to have to weigh all this out. after 9/11, weigh all this out. after 9/11, we saw the pennsylvania avenue

in front of the avenue —— in front of the white house was shut down. it has not reopened, it is a pedestrian mall area. there may be some ebbs and flows, increased securities, but the main security is always going to be the us capitol police at the us capitol. they have done an amazing job. the us capitol has been attacked in the past. we even had someone fly a small plane, a 1—man operated plane to the west lawn of the capital. the two officers were killed in 1998 from a man who suffered from mental illness, and they have been other incidents that have taken place around the us capitol. it is a magnet for people with issues to show up there. and so this is something that security is going to have to really look into for the future. , future. indeed they will. thomas _ future. indeed they will. thomas o'connor, - future. indeed they will. j thomas o'connor, thank future. indeed they will. - thomas o'connor, thank you so much for your type of study element thank you very much for having me. ==

element thank you very much for having me-_ having me. -- thank you very much mattingly. _ a minneapolis homicide investigator has said police officer, derek chauvin, used "totally unnecessary" deadly force when kneeling on george floyd's neck during an arrest last may. he was giving evidence on day 5 of the trial of mr chauvin — the white, former officer, accused of killing mr floyd. here's a bit of what lieutenant richard zimmerman had to say, responding to questions from the prosecution. what is your, you know, your view of that use of force during that time? totally unnecessary. what do you mean? well, first of all, pulling him down to the ground facedown and putting your knee on a neck for that amount of — that amount of time, it'sjust uncalled for.

i saw no reason why the officers felt they were in danger, if that's what they felt. and that's what they would have to have felt to be able to use that kind of force. our correspondent, lebo diseko, is in minneapolis and has been watching the trial. today has been very much about the police response. lt zimmerman, one of the longest—serving and most respected officers here in minneapolis, telling the court that in his 35 years on this force in minneapolis, he has never been trained to kneel on someone's neck and that is because it constitutes deadly force. also talking about the fact that once somebody is in handcuffs, they no longer constitute the same level of threat. and really saying that as a police officer, you have a duty of care to somebody once they are handcuffed, that their safety is your responsibility.

while one more piece of news from the us. major league baseball has announced it's moving its all—star game out of atlanta following the state of georgia's adoption of a new law that affects the right to vote. critics of the new legislation claim it makes it harder for black people and other minorities to vote in elections. the announcement comes a day after president biden called for the game — which was set to be at the home of the atlanta braves — to be rescheduled. the sport's commissioner said baseball supported voting rights for all americans. let's get some of the day's other news. taiwanese prosecutors have sought an arrest warrant for a construction site manager whose truck is suspected of causing a train accident in which at least 50 people died. the train hit the lorry that slid onto the tracks from the building site causing hundreds of people to be trapped for hours. the train was packed with local tourists travelling to celebrate a local holiday and is the island's worst railway disaster in decades.

officials from tehran and washington will travel to vienna next week, as part of efforts with other world powers to revive the 2015 iranian nuclear deal. the us and iran are not expected to hold direct talks. but russia has said the talks are on the right track. the iran nuclear deal was scrapped by president trump's administration, after he accused tehran of breaking the conditions. india's cricket legend, sachin tendulkar, has been hospitalised after testing positive to coronavirus earlier this week. the former captain said he had decided to go to a hospital in mumbai �*as a matter of abundant precaution under medical advice', and he added that he was hoping to be back home in a few days. the japanese scientist isamu akasaki, who won a nobel prize for developing energy efficient led lighting, has died at the age of 92. professor akasaki was jointly awarded the prize for physics

in 2014 along with two other scientists. the nobeljury described their invention of the blue light—emitting diode as revolutionary. stay with us on bbc news, still to come: forget a bonnet, get some scuba gear — why the easter bunny is heading underwater. the accident that happened here was of the sort that can, at worst, produce a meltdown. in this case, the precautions worked but they didn't work quite well enough to prevent some old fears about the safety features of these stations from resurfacing. the republic of ireland has become the first country in the world to ban smoking in the workplace.

from today, anyone lighting up in offices, businesses, pubs and restaurants will face a heavy fine. the president was on his way out of the washington hilton hotel, where he had been addressing a trade union conference. the small crowd outside included his assailant. it has become a symbol of paris. 100 years ago, many parisians wished it had never been built. the eiffel tower's birthday is being marked by a re—enactment of the first ascent by gustave eiffel. this is bbc news, the latest headlines: police guarding the capitol building in washington have shot and killed a man who drove his car into two police officers. one of the officers has died. a minneapolis homicide investigator has said police officer derek chauvin used "totally unnecessary" deadly force when kneeling on george floyd's neck during an arrest last may.

let's talk evolution now, and new research suggests the asteroid impact that killed off the dinosaurs also gave birth to our planet's tropical rainforests as we know them. a group of scientists has spent the past two decades investigating fossil leaves and pollen from across colombia and has finally gathered enough data to publish its findings in the prestigious journal science. i'm joined now by paleobiologist dr monica carvalho from the smithsonian tropical research institute, who authored the study. thank you so much for coming on the programme. thank you so much for coming on the programme-— the programme. thank you very much for having _ the programme. thank you very much for having me. _ the programme. thank you very much for having me. so - the programme. thank you very much for having me. so lots - the programme. thank you very much for having me. so lots ofl much for having me. so lots of research and _ much for having me. so lots of research and data _ much for having me. so lots of research and data gathered, i much for having me. so lots of. research and data gathered, and what is the headlines from your findings? 50 what is the headlines from your findinus? ., ., findings? so we found that after the — findings? so we found that after the impact _ findings? so we found that after the impact or - findings? so we found that after the impact or with . findings? so we found that| after the impact or with the impact, 45% of tropical species

disappeared, and it took about 8 million years for diversity to recover. (crosstalk) 8 million years is obviously a huge expanse of time, and when it did come back, what was different? forests were very different. so forests — forests were very different. so forests that came back resemble a lot rainforests that we know today, — a lot rainforests that we know today, they were dominated by flowering plants, they were very— flowering plants, they were very dense and they had the same — very dense and they had the same levels of intense ecological interaction that we see today. in the age of dinosaurs, that was not the case — dinosaurs, that was not the case the _ dinosaurs, that was not the case. the dominant plants were not flowering plants, it was a mixture — not flowering plants, it was a mixture of ferns, conifers and flowering _ mixture of ferns, conifers and flowering plants, and it was actually— flowering plants, and it was actually a pretty widely open rainforest back then. find actually a pretty widely open rainforest back then. and why the difference, _ rainforest back then. and why the difference, why _ rainforest back then. and why the difference, why the - rainforest back then. and why l the difference, why the change do you think when it came back finally after all those millions of years? finally after all those millions of ears? ., , millions of years? that is the key question- _

millions of years? that is the key question. so... - millions of years? that is the key question. so... not- millions of years? that is the l key question. so... not exactly sure, _ key question. so... not exactly sure. we — key question. so... not exactly sure, we think that it could be a mixture _ sure, we think that it could be a mixture of factors, it could be a mixture of factors, it could he that — a mixture of factors, it could he that in— a mixture of factors, it could be that in the past dinosaurs actually— be that in the past dinosaurs actually helped keeping the forest — actually helped keeping the forest open, something very similar— forest open, something very similar to _ forest open, something very similar to what happened in the african — similar to what happened in the african savanna with large elephants knocking down trees, it could — elephants knocking down trees, it could be that there was a selective _ it could be that there was a selective extinction against conifers _ selective extinction against conifers in the tropics during the extinction event, or it could _ the extinction event, or it could he _ the extinction event, or it could be that the asteroid's impact. _ could be that the asteroid's impact, all the ash and the vaporised rock and dust that was — vaporised rock and dust that was thrown out into the sky, fell down _ was thrown out into the sky, fell down again and acted kind of as— fell down again and acted kind of as a — fell down again and acted kind of as a fertiliser, that enabled flowering plants to actually take over.- actually take over. that is really interesting - actually take over. that is really interesting and - actually take over. that is really interesting and is l actually take over. that is - really interesting and is there anything we can take from what happened and apply it to today? this is an example of a global ecological catastrophe, and even — ecological catastrophe, and even though it was really fast, it is something that we can

relate, _ it is something that we can relate, or— it is something that we can relate, or it is an analogue to the rate — relate, or it is an analogue to the rate at— relate, or it is an analogue to the rate at which we are destroying natural ecosystems today, — destroying natural ecosystems today, and kind of tweaking the global— today, and kind of tweaking the global climate. so the bottom line global climate. so the bottom iine is— global climate. so the bottom line is that once rainforests io line is that once rainforests go out, _ line is that once rainforests go out, they will not come back _ go out, they will not come back. something different will come back and it will take millions of years for that. i millions of years for that. see, millions of years for that. i see, monica carvalho, millions of years for that. i see, monica carvalho, thank you for coming on. the netherlands is suspending the use of the astrazeneca coronavirus vaccine for people under the age of 60, as a precautionary measure. it follows five reports of cases of blood clots in women who'd been vaccinated, out of a total of 400,000 people who've been given the jab. one of the women died. germany took a similar step on tuesday. meanwhile the uk's medical regulator revealed there have been 30 cases of rare blood clotting in people who've had the oxford—astrazeneca jab and seven people have died. that's out of a total of 18 million administered doses in the uk.

our science correspondent rebecca morelle explains more. these clots are unusual in that they're associated with low platelet levels, and platelets are a type of blood cell that normally cause bleeding, not clotting, and these clots can affect the brain, too. so, what needs to be unpicked is whether these are happening naturally or whether they're a really rare reaction to the astrazeneca jab. the incidence is low, so 30 cases out of 18 million jobs. so that's about one event in every 600,000 astrazeneca vaccines. and the uk regulator said there have been two cases of brain blood clots with the pfizer vaccine, too, but these don't have the low platelet counts associated with them, so they're slightly different. but these clots have caused some countries to actually restrict who they give the vaccine to. so, today, the netherlands has announced that it's not going to be giving the astrazeneca jab to people under the age of 60.

germany are doing the same thing, too, but the uk is continuing with its vaccine roll—out. and the uk regulator stresses, along with the european medicines agency and the world health organization, and the protection that they offer from coronavirus far, far outweigh any potential risk. so, their message is, if you are offered the vaccination, to go ahead and take up that offer. russian state media have released a series of videos apparently intended to discredit the jailed opposition figure alexei navalny. two days after the critic of president putin declared a hunger strike, pro—kremlin media published clips of him walking without a limp to dispute claims mr navalny is suffering from leg and back pain. mr navalny began his hunger strike saying he'd been refused access to a civilian doctor, and that the russian penal colony is

a torture facility. still in russia, a medical team has successfully completed open heart surgery on a patient, as firefighters battled to control a serious fire at a hospital in the far east of the country. the leader of the heart unit said his team had to do everything to save their patient. gareth barlow reports. as smoke billowed out of the building, firefighters rushed in. emergency services scrambled to evacuate more than 120 patients being treated at the tsarist—era hospital. amid the chaos, one team of medics valiantly carried on. eight doctors and nurses performed a two—hour open heart operation. with electricity cut by the fire, an emergency power cable was fed into the building to keep vital life—support systems operational. translation: when smoke came in, we installed special— electric fire brigade fans

to evacuate the smoke from the first floor and from the operation room. the operation was a success, and the patient safely transferred to another unit. no one was injured by the fire. however, the impact of the blaze will be keenly felt, as the hospital is the only in the region with a specialist heart unit. all around the world, despite the global pandemic, millions of people will be marking the easter holiday. it is of course one of the most important dates in the christian calendar — but plenty of non—believers will be celebrating too. for them it's more about confection than resurrection, as tim allman explains. the easter bunny gets everywhere these days. here he is underwater, off the florida keys. well, actually, this is captain spencer slate,

a local scuba—diving operator. he is setting up a somewhat elaborate aquatic easter egg hunt. it is all in a good cause, raising money for local children in need. and in case you're wondering, all the eggs have non—toxic colouring and are environmentally friendly. speaking of eggs, take a look at these. in hungary, there is a long easter tradition of decorating them, intricate designs, delicate paintwork. little oval works of art. translation: over 30 years i have got to know the egg i as a material to work with. it may be very thin but it is still malleable. so we know each other, the egg and i, me and the egg. these eggs at london zoo are not quite as impressive but they do theirjob. every year, treats are hidden away by the keepers and the monkeys go

looking for them. and notjust the monkeys — the meerkats also like to get involved. across the other side of the world, a similar story at this park in new south wales. the local wildlife getting into the swing of things. although this koala still prefers eucalyptus leaves to easter eggs. before i go, here are some pictures of the tokyo 2020 olympic torch making its way through japan's central nagano prefecture. the torch would normally then be carried to the more western city of osaka, but authorities there are set to discuss plans with the 2020 tokyo games organisers to cancel that leg of the torch relay, due to the region's covid restrictions. the 121—day relay is seen as the first major test of olympic organisers' ability to hold a large event under

strict coronavirus curbs. that's it from me, get me any time on social media at lvaughanjones. this is bbc news, goodbye. hello there. it's likely to be a dry day for most of the united kingdom today, but there will be contrasts. where we keep the cloud as we had yesterday, temperatures will be held into high single figures, but in the sunshine, potentially 14—15. now, under the starry skies, that's where we see the frost as we start this saturday morning, but you can see the thicker cloud across northern scotland, central and eastern england, perhaps east wales. and there could also be a little bit of mist and fog where we've kept the clear skies as well. but the day is likely to give us quite a bit of cloud across central and eastern areas. it's likely to lift a little as we go through the day and the skies brighten. similarly so across northern scotland, we keep quite a bit. for the likes of lincolnshire, east anglia and the south east, though, it could remain overcast all day. and with that keen breeze

still quite gusty through in the sunnier spells. now, as we go through the evening and overnight, we tend to thicken our cloud in the north, but under the starry skies elsewhere, again we can expect a touch of frost. but you may have noticed the approach of some rain for the north of scotland, and that's the start of the transition to much colder air. it's this particular weather front here, as you can see, and behind it, there's arctic air following. so, we are going to have another blast of cold air as we head through in towards easter monday, but for sunday, easter day, a little bit of mist and fog around. actually, we should see a bit more sunshine for england and wales, but cloudier skies with rain for scotland followed by snow and cloudier skies for northern ireland. eventually, we'll see some of that wet weather coming in through the afternoon. but notice the temperatures. we've lost that keen north—easterly. they're a little bit higher temporarily. but overnight sunday into monday, that weather front introduces that colder air right the way across the uk, an arctic blast for all of us. and notjust the cold air, but a strong to gale—force north wind, as well, which will accentuate the chill.

clearly, the showers are quite prevalent for northern scotland, but they may well work their way down through the irish sea, down the east coast of both england and scotland as well. but there should be some sunshine between, but itjust will feel much colder, more like winter. these are the temperatures on the thermometer, but you add on that wind—chill, and it will feel significantly colder. so, big changes afoot, and that may well last into the start of the new week into tuesday, as well, as you can see. as ever, you can keep up to date on the weather on the website. bye— bye.

this is bbc news — the headlines: a police officer has been killed in an attack near the us capitol building in washington after a man drove his car into two officers — before getting out of the vehicle and lunging at them with a knife. the man was then shot by police. he later died. a minneapolis homicide investigator has said police officer, derek chauvin, used "totally unnecessary" deadly force when kneeling on george floyd's neck during an arrest last may. mr chauvin denies the charges against him. the netherlands is suspending the use of the astrazeneca coronavirus vaccine for people under the age of 60 — as a precautionary measure. it follows five reports of cases of blood clots in women who'd been vaccinated — out of a total of 400,000 people who've been given the jab.