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. remaining calm under the pressure — the life—saving operation that took place while a fire was raging. and — a different big bang — new research suggests the asteroid that killed off the dinosaurs may have helped create the rainforests.

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 at the capitol. 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.

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. well, earlier i spoke to fbi special agent thomas o'connor who for over two decades worked on thejoint terrorism task force in the washington field office. we began by discussing how this latest incident highlights the dangers faced by officers in the us capitol. it certainly does and it shows that the threat continues, whatever that threat may be from, and as your correspondent 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 scrubbing 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 with a combination of that, is what led

to this incident. the us capitol, 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 thejob they did. this was not a breach of security, this is what the security does. it stopped the vehicle from getting in, and those officers did theirjob and sadly one was killed and one was injured. you touched 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 there? is it something like what we can all see, looking at social media feeds— what are the other avenues they will be exploring?

it is, social media in this day and age really does shine a light into the mindset of the person that is being investigated, but along with that there'll 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 particularly have to be the reason the person did it, it could be mental illness that was spurred on by that conspiracy theories and ideological followings, but the mental illness is what pushed them over the edge, and we're seeing a lot more of that mental illness playing into many of the groups that were involved in the capitol takeover, many of those people have the same type of issues. it's the pandemic, the lockdown, being kept on the computer mostly 2a hours a day. we're having these issues, they're going to be springing up, i'd say around the globe, actually. 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 five 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 period? 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, isjust 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. major league baseball has announced its 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. joining me now is baseball columnist bill shaikin from the la times — who wrote last week that major league baseball should move the all star game. i don't know how much credit you can take but clearly some. they have listened to you. are you surprised that they have? i am a little bit. majorly baseball has been in this situation before. ten years ago, there was a controversy of law in the state of arizona and the same calls were made, there had to be a boycott, major

league baseball had to move the game, and they went on with the game, and they went on with the game as scheduled but social justice has changed a lot in america, especially after last summer and the summer of protests, and a summer in which businesses and sports leagues vowed to listen more carefully to the public and to the athletes that play their game, and i think in this case, majorly raised bull is very aware that there wasn't really aware that there wasn't really a need for a summer festival that would turn into a debate about voting rights, there was about voting rights, there was a clear right and a clear wrong, and there was a clear decision to be made, so rather than put out a strongly worded statement, major league baseball took action. that is really interesting. _ baseball took action. that is really interesting. so - baseball took action. that is really interesting. so by- baseball took action. that is| really interesting. so by your argument, what you are saying is we could see more of these kinds of decisions in the future? i kinds of decisions in the future? ~ , ., kinds of decisions in the future? ~ ., future? ithink so. folks in georgia— future? ithink so. folks in georgia that _ future? ithink so. folks in georgia that are _ future? ithink so. folks in georgia that are upset - future? i think so. folks in l georgia that are upset about this law appealed to corporations across america to take whatever action they could and in this case, the difference is that coca—cola and delta are companies that

are both based in the city of atlanta. they have come out with statements. but they are not about to move their headquarters and cost thousands of people theirjobs. in this case, majorly raised bull had a simple action, with one game, an exhibition game anyway, it doesn't really count for anything in the standings, with the idea that if this law is changed to or three years from now, major league baseball can bring the game back. i now, major league baseball can bring the game back.— bring the game back. i should 'ust sa , bring the game back. i should just say. just _ bring the game back. i should just say, just for _ bring the game back. i should just say, just for people - bring the game back. i should just say, just for people who l just say, just for people who don't follow baseball, could you tell us in a couple of sentences, what actually is this game? it sentences, what actually is this game?— this game? it is called the all-star — this game? it is called the all-star game, _ this game? it is called the all-star game, it - this game? it is called the all-star game, it is - all—star game, it is essentially a practice game. a showcase for the game's best whether you win or whether you lose, it does not matter, so it fans a chance to see their favourite players every year in one game. the best teams in the

best leagues. one game. the best teams in the best leagues-— best leagues. good to have you on, best leagues. good to have you on. thank _ best leagues. good to have you on. thank yon _ 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 crash in which at least 50 people died. the train hit the lorry after it slid onto the tracks from a nearby building site. the train was packed with local tourists travelling to celebrate a local holiday and is the island's worst rail disaster in decades. 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. stay with us on bbc news — still to come:

the show might go on — more than a year after closing their doors — the theatres of broadway partially re—open. 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. 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 world 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. new research suggests the asteroid impact that killed off the dinosaurs also gave birth to our planet's tropical rainforests as we know them.

paleobiologist, doctor monica carvalho from the smithsonian tropical research institute, is one of those researchers and joined me to explain the study. 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. sorry — 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 that came back resemble a lot rainforests that we know today, they were dominated by flowering plants, they were 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. the dominant plants were not flowering plants, it was a mixture of ferns,

conifers and flowering plants, and it was actually a pretty widely open rainforest back then. i see. and why the difference, why the change do you think when it came back finally after all those millions of years? that's the key question. so... we're not exactly sure, we think that it could be a mixture of factors, it could be that in the past dinosaurs actually helped keeping the forest open, something very similar to what happened in the african savanna with large elephants knocking down trees. it could be that there was a selective extinction against conifers in the tropics during the extinction event, or it could be that the asteroid's impact, all the ash and the vaporised rock and dust that was thrown out into the sky, fell down again and acted kind of as a fertiliser, that

enabled flowering plants to actually take over. our thanks to monica carvalho there. to algeria now where thousands of anti—government protesters took to the streets in the capital algiers, demanding democracy, fair elections and judiciary. the country's protest movement was interrupted by the coronavirus pandemic, and these latest demonstrations mark a resumption in the so—called hirak movement. dozens of activists remain behind bars despite the current president tebboune's promises to overhaul the country's institutions. danai howard reports. thousands filled the streets of algiers on friday, chanting along live and algeria that is not military. they are calling for an overhaul of what they say is a corrupt political system and an end to the army's involvement in politics. friday's demonstrations mark the resumption of the weekly

street protests that were suspended last year because of the covid—i9 pandemic. their determination is not waned. translation: the determination is not waned. translation:— translation: the algerian eo - le translation: the algerian pebble are _ translation: the algerian people are still _ translation: the algerian people are still thirsty - translation: the algerian people are still thirsty for i people are still thirsty for freedom, they are still searching for complete independence. searching for complete indeendence. �* ,, �* independence. translation: the eo - le independence. translation: the pebble take _ independence. translation: the pebble take to _ independence. translation: the people take to the _ independence. translation: the people take to the streets - people take to the streets today— people take to the streets today to save algeria from the hands — today to save algeria from the hands of — today to save algeria from the hands of the ruling gangs, and to allow the people to regain their sovereignty so that they may— their sovereignty so that they may be — their sovereignty so that they may be free in their affairs, freedoms, human rights. justice is a popular demand. the leaderless _ is a popular demand. the leaderless protest - is a popular demand. iie: leaderless protest movement known as hirak began two years ago and change the face of nigeria's leadership. in november 2019, widespread protests push the military to oust the former president who had been the country's leader for nearly 20 years. a month later, the new president was named in an election that saw a

record 33% low voter turnout. protesters then and now save the election was a charade. in a bid to quell the protest movement, president tebboune recently pardoned dozens of jailed activists and says he will reform the government, but has not been enough of these demonstrators who see his government as a continuation of the leadership they have been fighting against for more than two years. danai howard, bbc news. russian state media have released a series of videos intended to discredit the jailed opposition figure alexei navalny. two days later, program when media published video of him walking without a limp to dispute claims he is suffering from leg and back pain. mr navalny began his hunger strike, saying that he had been refused access to a civilian doctor and the russian penal colony as a torture

facility. staying in russia with a different story. a russian 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. gareth barlow, bbc news. to new york now, where the city's famous broadway theatres, art and entertainment venues are beginning to reopen at limited capacity. theatres have lain empty as the city battled against the covid pandemic, but from friday, theatres are allowed to reopen at 33% capacity. new york city's mayor, bill de blasio, says he's keen to get theatres back up and running again, with a full reopening by 2021. kelsey lu is a cellist in "this is not a test", performed at the shed threatre, one of the first venues in new york to reopen this weekend. she spoke to me a little earlier.

i never knew that i would be as excited to perform again as much as i am now in this lifetime. any nerves at all, not about the performing because i'm sure you're not nervous about that, but the limited audience and the procedures that everyone has to go through to get the performance up and running? i think that at this point we are all pretty used to having rules and regulations, but i think what really matters is the music, and that's what shines through and the energy that is in the room, and everyone just being excited to perform again, and to see music and to feel it, and experience — experience something that we've all missed for so long. and so yeah, that probably is going to be a little jarring, but once it all starts, that will dissipate and fade away. and how has this period been foryou, i'm presuming

the longest period without playing and performing in your career? yeah, it has been honestly incredibly depressing. i mean at first it started out pretty nice because i hadn't had so much time to myself, and not being on the road and touring and i felt this new surge of energy and inspiration. and then the loneliness and everything that, i don't know, time that i was faced with, that performance is such a huge part of living and thriving for me. it is my lifeline, and having that exchange of energy between audience and... people, and it really started to affect me, and my mental state, so i was yeah, it was really, really ha rd. i just want to pick up,

the importance of performing to that audience for you and your mental health, and it's going to be strange, not going back to what it was before, this is not thousands of people, this is a much smaller number, does that affect how you approach the performance? no, not at all. i mean that's how i started performing, i didn't start performing for thousands of people, i started performing for a few people. i started performing for small groups and intimate settings, and i love intimate settings. i think that's a special thing, and so i think also in that case, you are able to maybe even connect with people on a deeper level. so no, i don't think that would affect anything at all. kelsey lu there. before you go, here are some pictures of the tokyo 2020 olympic torch making its way through the nagano prefecture in central japan. the 121—day relay is seen as the first major test

of olympic organisers' ability to hold a large event under strict coronavirus curbs. i'm lewis vaughn jones. you've been watching 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 the channel, only eights and nines, but 13—15 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. that's where all the warnings are. 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. police have been questioning the manager of the construction site, whose truck is suspected of causing a train accident in which at least fifty 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. during the pandemic, video games have been a growing source of entertainment

and a way for many people to socialise online.