A handmade bomb exploded on a subway train in southwest London on Friday morning, and police are investigating the incident as a terrorist attack, authorities said.

At least 22 people were injured, health authorities said, after the blast in a train car near Parsons Green station. Police were called around 8:20 a.m. after reports of a fire on the train, which was traveling into London, they said.

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The train was crowded due to morning rush hour, and many of the victims suffered facial burns, according to local media. There have so far been no reports of fatality.

The BBC showed a video of a burning bag inside a train car at the station, and reported that the device was equipped with a timer.

It also showed aerial footage of passengers being helped off a train on elevated tracks.

"Our city utterly condemns the hideous individuals who attempt to use terror to harm us and destroy our way of life," London Mayor Sadiq Khan said in a statement. "As London has proven again and again, we will never be intimidated or defeated by terrorism."

British Prime Minister Theresa May issued a statement expressing her condolences to the people who were injured in the attack.

The station is in the southwestern part of London around a residential area near the north shore of the Thames River.

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