At least 22 people have been hospitalized after an explosion at the Parsons Green station of the London Underground.
The explosion occurred on the morning of Sept. 15 and was caused by a bucket bomb, according to The Telegraph. It is believed the device may have been set off with a timer and was not fully detonated.
A picture circulating on social media shows the device, a white flaming bucket with what appears to be wires hanging out of it, on the floor of one of the train's passenger cars.
Those who witnessed the explosion reportedly described it as a "fireball" and a "wall of flame." Many of those injured experienced "flash burns," although some were injured after being trampled during the panic the device caused as people tried to exit the train.
"I was on the train, about two carriages from the front, and I was talking with my friend and all of the sudden people started screaming and running," said 13-year-old Alex Ojeda-Sierra, who was on his way to school when the explosion occurred, according to the Watertown Daily Times.
"I dropped my bag and we started running," he continued. "My friend was ahead by a meter. I tripped and he carried on running. One man fell on me and I had my legs bent backwards and my right ankle got twisted and I started screaming that I had no air."
Although at least 22 people, including Alex, were hospitalized, none of their injuries were life-threatening. No one has been reported dead.
A manhunt for the bomber is underway, and police and British intelligence agency MI5 are working together in the investigation, The Telegraph reports. There is also an unconfirmed report that a suspect has been identified using CCTV surveillance cameras.
Roy Ramm, a former commander of specialist operations at Scotland Yard, told The New York Times that police will also look into the cause of the attack.
"Parsons Green is not emblematic or symbolic, and I think that will be a puzzlement for investigating officers, who will ask: Was it intended to be detonated or did it go off there by accident?" he said. "If you look at a list of target areas in London, Parsons Green would not be in the top 100."
Following the explosion, London Mayor Sadiq Khan took to Facebook to address the attack and to thank emergency responders.
"Our city utterly condemns the hideous individuals who attempt to use terror to harm us and destroy our way of life," the statement reads in part. "As London has proven again and again, we will never be intimidated or defeated by terrorism."