The Islamic State has claimed responsibility for a bomb attack on a packed London Underground train that injured at least 29 people.
"The bombing on a metro in London was carried out by a detachment of the Islamic State" group, it said in a statement published by its Amaq propaganda agency.
Prime Minister, Theresa May, calling the blast a "cowardly attack," said the government had raised the national threat level one notch to "critical," the highest.
The bomb exploded at 8:20 a.m. on an eastbound District Line train leaving the Parsons Green station in Southwest London.
"This was a detonation of an improvised explosive device," Assistant Commissioner Mark Rowley of the Metropolitan Police, a top counterterrorism official, said at a news conference.
He urged anyone who had seen what happened, or had taken photos or videos of the bombing, to come forward.
Officials said that 29 people were hospitalized, but none had life-threatening injuries.
"The train was packed, and I was down the other side of the carriage standing up, looking at my phone and then I heard a big boom and felt this heat on my face," NY Times quoted Natalie Belford, a beautician who was on the train.
"I ran for my life, but there was no way out. The doors were full of people and the carriage was too packed to move down."
It was the fifth terrorist attack in Britain this year, following a vehicular and knife attack near Parliament in March, a suicide bombing at a rock concert in Manchester in May, and a van and knife attack around London Bridge and a van attack outside a London mosque, both in June.