it follows a bombing on a london tube train during this morning's rush hour, 29 people were injured. police say the bomb was home made and only partially exploded — the prime minister urges us to be calm but vigilant. the public will see more armed police on the transport network and on our streets providing extra protection. commuters caught up in the attack tell of a large explosion on the train. this fireball wasjust this fireball was just going over your head and everybody's screaming. massive bang occurred. didn't know what happened, looked around and the first thing we saw was an orange sort of fireball circumventing the whole tube coming towards you. whoever planted the bomb is still on the run, so—called is have claimed responsibility, a massive police investigation is underway. also tonight:... sirens injapan — after north korea fires another missile over the country —

to international condemnation. i'm going to call this the end of mission. a bittersweet end to a space mission which circled saturn for 13 years sending back never before seen images. the unions call for a pay rise of nearly four per cent for some nhs workers. and a cultural milestone — the opening of africa's biggest ever museum of african contemporary art. and coming up in sportsday on bbc news: essex hail an ‘amazing season‘ as they celebrate their first county championship title in 25 years. good evening. the terror threat in the uk has been raised to the highest level — critical — meaning an attack may be imminent. it follows a bombing on a tube train in london during this morning's rush hour which the police are describing

as a "terrorist incident". thankfully, no—one died but 29 people have been treated in hospital, some suffering from burns. witnesses have spoken of a "flash and a bang" and then panic as commuters ran out of the station. it happened as a district line tube train pulled into the overground station at parsons green in west london at 08.20 this morning. the bbc understands that the bomb, described as a homemade device, had been fitted with a timer — but it failed to fully detonate. whoever planted it is still on the run. so—called islamic state have claimed responsibility. in a moment, we'll bring you latest on the investigation, but first our special correspondent lucy manning is in west london for us tonight, despite the injuries, with a bomb going off in the middle of rush hour, many will be thinking this was a lucky escape. this could have ended in tragedy. the day could have ended with very

many dead. but the day is ending with the terror threat level raised and with a bomber who, as the police put it, is still being hunted down. for those here who is commute this morning ended in tragedy, it's the realisation that they were in a carriage with a bomb. but luckily one that didn't properly explode. on the floor of the tube, still in flames, it was supposed to blow up the carriage. that bag is on fire. it caused panic, fear, some injuries, but thankfully it didn't kill. let's get away and moved to the end of the platform. at 8:20am, this train, packed with commuters, had just arrived at parsons green. it was loud enough to make me wonder what the bang was, i looked around and this wall of fire was just coming towards us. i turned left and saw the fireball surged towards my

side. luke walmsley was in the carriage listening to music. a bang then a flash to my left. almost immediately, sort of a surge of people screaming and running towards me. the improvised bomb was in a white bucket with wires attached in a lidl freezer white bucket with wires attached in a lidlfreezer bag. david nelson saw it partially detonate. lots of schoolchildren on the way to school. noticed this flash of light over the other side of the carriage. this heatwave. then just like a burst of flames. after you saw the flames what happened 7 flames. after you saw the flames what happened? panic. everyone pushing to get off. luckily the doors were open because we'd just popped doors were open because we'd just popped into the station. then a bit chaotic, people being thrown everywhere, people being trampled. there was people running over other people within the carriage. when i got outside the train i was able to see people, like, jumping off the train station towards the end of the

carriage. passengers on the train behind were helps down the tracks. children had their schooljourney interrupted in the most frightening manner. within minutes, armed police, fire crews and ambulances arrived. it was clear there were some injuries. no one allowed through here. burns and from the stampede after nearly 30 taken to hospital. this woman's commute to work ending in a very different way. relieved to be safe. peter crowley suffered burns to his head. there was a fireball above my head and there was a lot of people with facial burns and singed hair like myself. worst casualty eyesore, a gentleman had a pufferjacket that had all melted at the back. a large area around parsons green tube

station has been cordoned off and this afternoon the police announced they were evacuating local residents living closest to it, to allow them to try and make that device left on the train a bit more stable. so—called islamic state said it carried out this terror attacks, the police hunted the would—be bomber and the terror threat level to the uk was raised. the joint terrorism analysis centre, the independent organisation which is responsible for setting the threat level on the basis of the available intelligence, has now decided to raise the national threat level from severe to critical. this means their assessment is that further attack may be imminent. the army will now replace police officers at some locations as hundreds of detectives search for who plan this bomb. we are making excellent progress at the moment as we pursue our lines of inquiry to identify, locate and arrest those responsible. it is a

very complex investigation which is continued at speed with the full weight of the london counterterrorism policing resources assisted by colleagues from around the country and our intelligence agency partners such as mi5. for those who walked out of the tube carriage today, there is, of course, relief. lucky. i'll go home, give my wife and kids a big cuddle tonight. happy wife and kids a big cuddle tonight. happy to be here. but with a bomb on the run and fears another attack could be imminent, these are tense times for those whose job it is to catch him. lucy manning, bbc news, parsons green. the head of counter—terrorism says hundreds of detectives are now involved in the investigation. the bomb is being examined by forensic teams and officers are looking through cctv at the station for clues about who planted it. our security correspondent gordon corera takes a closer look now at the investigation and where it might lead. the device at the heart of the

investigation. the ongoing hunt for the person who planted it is now led to the uk's threat level moving up to the uk's threat level moving up to critical. its highest level. the makeshift bomb will have yielded some clues in that hunt. like these wires coming from the bucket, used to try and trigger an explosion. they look similar to these christmas tree lights that a birmingham man planned to use in a home—made device before he was arrested. such improvised devices do not always go off properly. that was the case on july 212005. experts believe today's bomb also didn't explode as intended. the size of the device employed was quite significant. and had that device functioned in its intended and designed mode we'd have seen intended and designed mode we'd have seen considerable casualties. many people injured and probably many

people injured and probably many people killed. the explosive may have been a compound called tatp, this footage from brussels airport and metro shows the devastation when it decimates properly, more than 30 we re it decimates properly, more than 30 were killed. it is thought to have been used in the manchester arena attack this year, that involved a suicide bomber. but today's attacker wa nted suicide bomber. but today's attacker wanted to get away and used a time. that is similar to damon smith, seen here leaving a timed device at north greenwich a year ago, which was spotted before it went off. today, hundreds of counterterrorism detectives have been deployed in this investigation. they've been fore nsically this investigation. they've been forensically analysing this device, looking for fingerprints and dna. they've also been scouring cctv images looking for an individual carrying this bag onto the tube and then getting off without it. that will have been the starting point for their manhunt. m15 are helping

the investigation. they will want to know if the individual was part of a group or acted alone and, as has often been the case recently, if they were previously known to authorities. unfortunately it would not be a surprise, this concept of a label chile lone wolf would more accurately be described as a known world. the tax when this happened have been committed by individuals who were known in some way to either the counterterrorism police or m15 beforehand. officials here have reacted with irritation to this tweet from donald trump. theresa may responded that it was never helpful to speculate about an ongoing investigation. for the fifth time this year, the country is dealing with the aftermath of a terrorist attack. and tonight, with

no sign yet of an arrest, officials felt they had to raise the threat level amid fears the danger has not yet passed. is it a surprise the threat level has been raised or is this what we should expect given a manhunt is under way? no, i don't think it's a surprise, it is an independent decision, not a political decision, it's taken by thejoint terrorism political decision, it's taken by the joint terrorism analysis centre, officials there housed within m15. why have they done it? basically as long as there is a persian with murderous intent still at large i think they felt they had to. —— as long as there is a person with murderous intent. the possibility, the fact they can't rule that out, has meant they felt they had to take it to the highest level, critical. what does it mean for ordinary people? i don't think people are expected necessarily to change their behaviour in any way, but they might see some differences. it means for insta nce see some differences. it means for instance that soldiers will take

over guarding certain sites which, in turn, will free up armed police, so people can expect to see more armed police on the streets on things like trains. a lot of sensitive sites and buildings have their own security protocols which they put in place when the threat level goes to critical. chelsea football clu b level goes to critical. chelsea football club tonight has said most of their site at stamford bridge will be closed tomorrow including the shop and for the game with arsenal on sunday people should come at least one hour early because there will be more bag checks, that is the kind of thing you can expect to see in a number of places. it creates a burden on resources, is not the decision officials take lightly. they'll want to bring it down back from critical to severe as soon as down back from critical to severe as soon as they can, but that will depend on progress in the manhunt and as long as that person is still at large who planted the device, it'll be hard for them to bring it down from critical. that hear more about the manhunt. home affairs correspondent daniel sandford is outside scotland yard. what more can you tell us about the investigation

and manhunt? an hour and a half ago mark rowley, assistant commissioner in charge of fighting terrorism across the uk, talked about hunting the suspects down. i think this is the suspects down. i think this is the most significant terrorism manhunt london has seen since those failed bombings of the 21st ofjuly 2005. counterterrorism detectives are keeping the card is pretty close to their chest tonight, for example they haven't taken the option of going public with an image of their suspect, asking the public for help trying to track them down. they haven't even really gone so far as to say how much progress they have made working out where the bomb got the train, how much progress they have got in getting an image of the suspect or a name of the suspect. from conversations i've had to night i get the impression they are making good progress on all of those, they just don't want to tell the public at this stage how much progress they are making. one thing they haven't made progress on is capturing the

suspect or any accomplices he may have had. that will be concerning officers because there is a sense london has been lucky today. that they've survived a tube bombing without anyone being killed. but officers won't want is for that luck to change, they will want a situation where this bomber or any accomplices succeed in carrying out another attack. north korea has fired another ballistic missile across japan, creating new tension in the region after its nuclear bomb test less than two weeks ago. the rocket travelled the furthest of any so far, more than 2000 miles from sunan, over the japanese island of hokkaido, and into the pacific ocean. it's sparked a new round of international condemnation. the un security council tonight strongly condemned the "highly provocative" launch and called for an immediate halt to their actions. rupert wingfield hayes reports from niigata in japan. siren wails in northern japan, friday began with this very

unpleasant wake—up call. speakers blared out warnings. commuters were cleared from railway stations, and trains halted. that's a nice wake—up call. foreign tourists were left bemused by what was going on. far above, a north korean missile was flying past. this behind me is the sea ofjapan. we've come up from tokyo because this is the place that is most affected. this is the place where this morning they were woken up by those sirens and by that message that a north korean missile was flying overhead. for the people who live here in towns and cities along this coast, it is the second time that has happened in less than three weeks. this afternoon, we found kazuyoshi ishida playing with his young daughters and fretting about how to protect them. translation: i want to protect my kids but we don't have a basement. we have nowhere to hide.

the missile takes only ten minutes to reach japan. what can we do in ten minutes? erika shinbo told me she is frustrated by japan's refusal to talk to north korea. translation: the sirens, to scare people, there's nothing you can do. so what is the point? the government needs to have a real policy. it needs to talk to north korea. this is the type of missile that is thought to have been fired. it flew further than any north korean rocket has ever gone before. in tokyo, prime minister shinzo abe marched out to face the cameras again. "if it continues down this road", he said, "north korea will have a dark future". but his words have an increasingly hollow ring. beneath this house, one person has taken matters into his own hands. behind a heavy steel door, seiichiro nishimoto takes me

into his own nuclear bunker. translation: since these missile launches began, i've had so many calls about the air filtration system. i've had at least 800 enquiries this year. he is safe in his bunker, but the rest of japan is wondering what it can do, and when the next missile launch will come. rupert wingfield hayes, bbc news, niigata, northern japan. in a moment we'll talk to our north america correspondent, nick bryant, who's at the un in new york. but first let's go to our china editor, carrie gracie, who is in shenyang on the china and north korea border. china is pretty much north korea's only ally in the world but so far is reluctant to take the kind of action against north korea that the us has been calling for.

yes, fiona. i'm in north—east china, near the north korean border, as you say, an area where they remember with pride the korean war. memorials like the one behind me, which they call a war against the united states, to assist career. that gives a sense of some of the difficulties they face, that historical memory, economic reasons, strategic reasons, and reasons of sheer soul reservation against a vengeful north korean dictator, all those reasons holding them back from abandoning the north korean regime absolutely. so they have been trying to hold a position, as you see again today, with their defensive response to american pressure for more acute sanctions against north korea. they say they are implement existing un resolutions to the letter. all sides

need to ratchet down the tension, according to china. at the end of the day, with every provocative north korean move, missile test, nuclear test, china is coming under increasing pressure. the ground beneath it is shrinking, notjust internationally, but at home, because the chinese public is getting increasingly concerned about the nuclear threat, and china's foreign policy experts are increasingly saying that north korea is now a strategic liability, not an asset. nick bryant, the us seems to be taking a different tone in response to north korea from its previous more aggressive statements. yes, especially from donald trump, the president. none of the fire and fury rhetoric from the summer, none of the locked and loaded tweets. he has not engaged in any form of digitised sabre rattling on his

twitter feed today. nor has the trump administration called for fresh sanctions. we have seen two fresh sanctions. we have seen two fresh sets of sanctions passed here at the un security council in the past month. the trump administration are saying today that those sanctions should be given time to ta ke sanctions should be given time to take effect. but american patience is clearly running thin. sanctions have not worked before, and the national security adviser today said, we can't keep kicking this can down the road because we have run out of road and we have run out of time. he said there is a military option, although he did say that the trump administration's preference for now was not to use it. next week at the united nations, world leaders will gather for the annual un general assembly. north korea will be very high on the agenda. donald trump will be here, but his chinese counterpart won't be, and i think that reduces the chances of a

diplomatic breakthrough. nick bryant at the un in new york, thank you. it is the pioneering spacecraft that has given us some of the most remarkable images ever seen of the planet saturn. for 13 years, cassini has documented extraordinary discoveries from its rings and moons and transformed our understanding of the sixth planet from the sun. today was its final mission, plunging into saturn's atmosphere at more than 75,000mph to be burnt up and destroyed. our science editor, david shukman, examines one of the most successful space explorations in history. it's been a journey that sounds like something from science fiction. nasa conjuring up animations of the cassini spacecraft flying around the spectacular rings of saturn. but this really did happen and these are some of the images the mission actually captured. the planet seen from closer than ever before. the strange detail of its rings. a jet stream in the shape of a hexagon. and an utterly weird

collection of moons. but today, the expedition had to come to an end. i'm going to call this the end of mission. at mission control in california, hugs and applause. for many it's been the work of a lifetime. and no surprise, there were very mixed feelings as the final signal reached earth. well, it's been a part of my life for 20 years. we've spent day in and day out thinking about cassini, planning the observations, focusing on the science. my career has been based on cassini, so it's really hard to see that go. saturn is the most distant world to have been explored for so long. and the cassini spacecraft, which is almost as big as a bus, has achieved something never attempted before. it's given us unprecedented views and these have led to dozens of discoveries. the mission is described

as one of the most remarkable journeys of exploration. while it's been orbiting saturn for a staggering 13 years. now, it's one of saturn's moons called enceladus that produced the most startling revelation. plumes of vapour were spotted blasting out of it. now this turned out to be water. so let's take a closer look inside what we now know, that under a covering of ice, there is an ocean. and scientists have come to an amazing conclusion. that in here there is every ingredient needed for life. this opens up a whole new realm of possibilities in the search for life beyond earth. and the discovery of conditions on moons like enceladus is a real breakthrough for scientists like linda, who started her career at nasa three decades ago when the mission began. we want to know, is there life on enceladus's ocean? could there be oceans inside of other moons? it will take future missions to go back and answer those questions.

the mission captured these images of saturn's moon, titan, and this is the sound the spacecraft recorded. to make sure cassini didn't contaminate any of the worlds where there may be life, it was sent to its destruction. but it has raised some tantalising new questions. david shukman, bbc news. the pressure on the government to lift its 1% pay cap on public sector workers has intensified after 1a health unions called for a rise for more than1 million workers in the nhs. in a letter to the chancellor, the unions, representing nurses, midwives and other support staff, are calling for an increase of nearly 4%. the government has said it wants their pay to be fair but also affordable to taxpayers. our health editor, hugh pym, reports. diane, who is a laboratory technician, has worked in the nhs for more than three decades. but the last few years have been the toughest, because of the pay cap. she's had to watch very closely what she spends on herself and her daughter.

it makes us all very angry. all public sector workers should have the cap lifted. we are alljust as important, we all work as front—line workers, we are all the cog in the wheel that keeps going round to make the nhs work. scrap the cap has been the court in protest against pay restraint. earlier this week the government lifted the 1% limit for police and prison officers. health unions now wants nearly four times that, paid for by two and a half billion pounds of new money. the total nhs budget in england is 110 billion. here's how the pay cap imposed after 2010 affected nurses and midwives. average annual wage rises in england have been under 1% since then. that was well below the inflation rate for much of that time. employers didn't comment on the specific wage increase demanded by unions, but in a significant move one group representing hospitals and other trusts in england said it was broadly sympathetic to the union's claim because of current

difficulties recruiting and retaining staff. i think it's absolutely understandable that the health unions have called for an end to the pay cap. we've seen austerity now biting for the past seven years. and it's absolutely critical that we see that pay cap lifted so that we get enough staff on the front line and we keep those staff that are there. devolved administrations will set their own pay policy. a government spokesperson said for england the priority was to ensure any settlement was fair, while also being affordable to taxpayers. but they know across the nhs there's real passion about getting more pay. hugh pym, bbc news. the pound has hit its highest level against the dollar since the result of the brexit vote lastjune. it follows comments yesterday from a senior bank of england figure who signalled that interest rates could rise "in the coming months".

the pound also gained against the euro, rising by 1%. up to 400,000 people in the uk may have had their information stolen, following a cyber security breach at a us credit monitoring firm. equifax revealed last week that it had been victim of a huge computer hack, involving the personal details of more than 143 million americans. the company discovered the hack injuly, but only informed consumers last week. the body of a british tourist killed in a suspected crocodile attack has been found in a lagoon in south—eastern sri lanka. 24—year—old paul mcclean, who worked for the financial times, had been on holiday in arugam bay, and is believed to have been washing his hands in a lagoon when he was killed. in a statement, the paper said it was "heartbroken" over his death. boasting 80 galleries and spread over nine floors, the zeitz museum of contemporary art africa is the continent's first museum

devoted to such an art collection. it's been created around a disused grain silo on cape town's waterfront and is backed by a german entrepreneur who owns much of the art on display. ahead of its official opening next week, the bbc‘s arts editor, will gompertz, has been to take a look around. table mountain, one of cape town's iconic sites, along with the city's spectacular coastline and the victoria and alfred waterfront, which now boasts a brand—new attraction, the zeitz museum of contemporary african art, which has been created by repurposing the harbour‘s imposing, long—redundant concrete grain silos. there was this extraordinary pair of buildings made from tubes. and it felt that its tube—iness was the thing that could be its spirit and character. we realised the tubes offered us this opportunity, if we carved a major space out of them and didn't fight them but enjoyed them.

they've made this unusual thing. he says his 80—gallery building is the biggest art museum to be opened in africa for over a century, and dedicated to showing contemporary african art, the majority of which is owned by this german businessman, who has his name above the door. we want to be as representative as possible of africa as a whole, which obviously is incredibly diverse. 5a countries, a huge continent. and there's only so much you can collect. our goal was always to just create a platform. and it's not us talking, but having the artists talk about africa. because for us it is important that africa writes its own history and its own future. we're just there to facilitate and help in exciting journey. some think that the zeitz mocaa has got it right, but others think it represents a partial, largely white male view of the african art scene. either way, there is a general agreement that the new museum is a significant and timely addition to the continent's cultural landscape.

we now have a space that is "of an international standard" where we can have our work housed. it gives a clearer understanding of the fact that we can operate on the same level as places like the guggenheim, or the tate. yeah, it's an important moment for us. for those artists exhibiting in this museum, or the many other gallery spaces popping up in this city and beyond, this is definitely a moment. the world is paying attention. they have a voice. the energy is here. in fact, it is quite possible that they will become the new international ava nt—garde. will gompertz, bbc news, cape town.