An improvised explosive device exploded on a crowded subway train in London during rush hour Friday injuring at least 22 people, according to police, in what is considered to be Britain’s fifth terror attack this year.
Police in the U.K. said the explosion on the train at Parsons Green station, in the southwest part of the British capital, was being treated as a “terrorist incident” and that no arrests have been made.
“There are many urgent inquiries ongoing with hundreds of detectives involved, looking at CCTV, carrying out forensic work and speaking to witnesses,” said Mark Rowley, head of counterterrorism for the Metropolitan Police, in a statement. “This investigation will be supported by our colleagues at MI5 bringing their intelligence expertise to the case.”
WATCH: U.K. politicians condemn what police are calling a terror attack
Passengers on board the packed subway described scenes of panic and chaos as fire engulfed the train and sent people running.
“As I approached the station everyone was piling out. People weren’t even running they were falling over each other,” said commuter Aaron Butterfield. “They were just fleeing.”
Luke Walmsley, 33, described “complete pandemonium, complete terror” aboard the train as a fireball and smoke raced through the subway car.
“We heard the first scream and we saw a flash and smoke and people started running immediately,” he told reporters in London, adding that people suffered burns to their head. “It was a really acrid burning smell.”
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London police and paramedics said the 22 people taken to hospital suffered mostly from burns and that no one was injured seriously.
“I was on second carriage from the back. I just heard a kind of whoosh. I looked up and saw the whole carriage engulfed in flames making its way toward me,” Ola Fayankinnu, who was on the train, told Reuters.
“There were phones, hats, bags all over the place and when I looked back I saw a bag with flames.”
Charlie Craven, who works in the financial sector, told reporters he saw people falling over, being crushed as commuters fled the subway.
“Literally within three seconds of putting your bag down, the doors just closing, we hear a loud explosion occur,” Craven said. “I looked around and saw this massive fireball and I can only describe it as a fireball, because that’s what we saw.”
Images posted to social media showed people with singed hair and burn marks.
Prime Minister Theresa May called a special meeting of the anti-terrorism Cobra committee for later Friday.
“My thoughts are with those injured at Parsons Green and emergency services who are responding bravely to this terrorist incident,” she said.
London Mayor Sadiq Khan condemned “the hideous individuals who attempt to use terror to harm us and destroy our way of life. As London has proven again and again, we will never be intimidated or defeated by terrorism.”
U.S. President Donald Trump tweeted: “Another attack in London by a loser terrorist. These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!”
Britain has seen a string of major terror attacks in 2017.
In March, a man drove a car into pedestrians on London’s Westminster Bridge killing four, before he stabbed a policeman to death outside parliament.
Another 22 people were killed in a suicide bombing at an Ariana Grande concert in Manchester in May and in June three Islamist militants drove into pedestrians on London Bridge before stabbing people at nearby restaurants and bars, leaving eight people dead.
In June, a man drove a vehicle into worshippers near a mosque in north London killing one.
— With files from Reuters.