A homemade bomb went off on a filled London Underground subway car this morning near Parsons Green that left 22 people injured. The police have announced they are treating it as a terrorist attack. From The London Times:

Officers believe that the blast was caused by an improvised explosive device and hundreds of detectives are now investigating, with the assistance of MI5.

Passengers on the District Line train fled in terror after a container in a plastic Lidl shopping bag appeared to explode near a train door, sending a fireball through the carriage. Most of those who injured following the incident at Parsons Green, southwest London, suffered “flash burns”; others were trampled in the rush to escape the packed carriage. No one suffered serious or life-threatening injuries.

The authorities have not made any arrests. They have identified a suspect from CCTV footage, though.

Witnesses have spoken out about the attack. The London Times continued:

Chris Wildish, who was on the train, told BBC 5live: “It was a white bucket, a builder’s bucket, in a white Aldi bag or Lidl bag. Flames were still coming out of it when I saw it and had a lot of wires hanging out of it — I can only assume it was done on purpose. It was standing against the door of the rearmost carriage.”

Sylvain Pennec, a software developer from Southfields, near Wimbledon, was about ten metres from the source of the explosion when fire filled the carriage.

“I heard a boom and when I looked there were flames all around,” he said. “People started to run but we were lucky as the door started to open.”

He described the panic as commuters struggled to escape the carriage, “collapsing and pushing” each other.

Mr Pennec stayed behind to take a closer look at what he believed was the source of the explosion. “It looked like a bucket of mayonnaise,” he said. “I’m not sure if it was a chemical reaction or something else but it looked homemade. I’m not an expert though.”

Authorities are currently trying to confirm that there are no other devices on the subway system. They also said this homemade device went off “prematurely” and let off some flashes as it burned.

This is the third terrorist attack in the UK this year. Back in June, terrorists attacked London Bridge and Borough Market, which killed seven people and injured 48. A bomb went off at an Ariana Grande concert in Manchester in May, leaving 19 dead and 50 injured.

In March, a man plowed his SUV into crowds of people on Westminster Bridge before he drove into the perimeter fence at parliament. After he exited his car, he stabbed one police officer before other officers shot him. That attack killed four people, including an American.