Terror strikes London once again, this time on a tube train.
At least 22 people were injured in a blast on the underground train at Parsons Green Station, Friday morning.
" We now assess that this was a detonation of an improvised explosive device. Hundreds of detectives involved looking at CCTV," Mark Rowley with the Metropolitan Police said.
Police believe a white bucket inside a bag, with wires and flames coming out, is the device that exploded.
"People were clearly injured. People were screaming, people were crying. I was falling over people myself," said one witness.
No one was killed. Most of the injuries are reportedly from flash burns.
ISIS has claimed responsibility for the attack. No one's been arrested so far.
This is the fifth attack in the U.K. this year.
"What we've seen over the last period isn't a spike. It's a shift in relation to attempts by terrorists to kill, to injure, and disrupt our way of life," London Mayor Sadiq Khan said. "And I can speak for Londoners: we are not going to allow them to do so."
President Trump called the attack a terrible thing and demanded tougher action.
"We have to be very smart. We have to be very, very tough," the president said.
Although the attack is still under investigation, President Trump made the following claims on Twitter.
"These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!"
New Scotland Yard is the headquarters of London's Metropolitan Police Service.
The president also said the U.S. Travel Ban should be far larger, tougher and more specific.