LONDON (CBSNewYork/AP) — UK officials have raised the country’s terrorism threat level to “critical” — meaning another attack is expected shortly.
Twenty nine people were hurt Friday when a homemade bomb exploded on a packed subway train during the morning rush hour.READ MORE: WATCH LIVE: Officials Provide Update After 1 NYPD Officer, Suspect Killed In Harlem Shooting
Metropolitan Police called the explosion a “terrorist incident,” the fifth in Britain this year.
“Detectives from the Counter Terrorism Command, part of the national counter-terrorism police network, are making fast-time inquiries to establish who was responsible and are working closely with the security services,” Metropolitan Police said in a statement. “So far there have been no arrests.”
The Islamic State group claims the London subway explosion was carried out by an affiliated unit. As CBS2’s Gavin Ramjuan reported, authorities in London have beefed up security as they continue to search for those responsible.
It happened around 8:20 a.m. Friday local time at the Parsons Green station in southwest London. Police said they were initially called to the scene for a report of a fire on a train.
“We believe the fire was caused by the detonation of an improvised device, which is being forensically examined,” police said.
Cell phone video from the subway car shows a white plastic bucket inside a shopping bag with what appear to be wires and a flame.
“Suddenly, I heard a big bang and I turned left and I saw the fireball,” witness Shu-Chen Warner said.
Sources told CBS News the device contained Christmas lights, a timer, and loose screws which may have been intended as shrapnel. It didn’t fully explode, but the noise was enough to trigger a stampede.
“We managed to pull ourselves away and literally just jump over the fence and then run down the track as fast as we can,” said passenger Charlie Craven.
The National Health Service says 21 people are being treated and eight others have already been discharged. The London Ambulance Service says it took 19 patients to hospitals, most with minor injuries. The others went in themselves.
Police say most of those injured by an improvised explosive device on Friday suffered from flash burns. They say there have been no reports of serious life-threatening injuries.
The device burst into flames aboard a train at the Parsons Green station during the morning rush hour. London police are conducting a wide manhunt for the person or persons responsible.READ MORE: With Tragic Shooting Of 2 Police Officers In Harlem, 5 NYPD Officers Have Been Shot In January
Counter-terrorism police are scouring the scene and searching security cameras to find out who put the bomb on board.
“There are many urgent inquiries ongoing now with hundreds of detectives involved looking at CCTV, forensic work and speaking to witnesses,” said Assistant Police Commissioner Mark Rowley.
Armed police shut down part of the train line and locked down schools in the southwest London neighborhood. Witnesses say children were on board when the blast went off.
“There was an unfortunate little boy who smacked his head on the ground,” one witness said. “They went flying.”
Some passengers had minor burns and singed hair from the heat that shot through the train car. Others were hurt in the rush to escape.
“Foot, head injuries from the stampede,” witness Luke Walmsley said. “It’s every man for himself when that happens.”
Police remain on high alert across London until the bomb maker and any other suspects are found.
The mayor of London, Sadiq Khan, said residents should stay “calm and vigilant” and said the city “utterly condemns the hideous individuals who attempt to use terror to harm us and destroy our way of life.”
Here at home, NYPD Commissioner James O’Neill tweeted photos of what appeared to be the white bucket and bag inside the London subway train and said the NYPD is closely monitoring the incident.
O’Neill said while there are no direct threats to the city, New Yorkers should “always remain vigilant” and aware of their surroundings.
“In New York we live with the reality that we are the most targeted city in the United States by terrorist plots,” John Miller added.
President Donald Trump also took to Twitter Friday morning. He said, “Another attack in London by a loser terrorist” and suggested the terrorists were known to British police.
“These are sick and demented people who were in the sights of Scotland Yard,” he said. “Must be proactive!”
Britain’s Prime Minister Theresa May responded that it’s not helpful to speculate on an investigation.MORE NEWS: Paterson Community In Mourning After 18-Year-Old Honor Student Robert Cuadra Killed By Stray Bullet
(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)