A 40-year-old man was arrested on Friday after stabbing five people in a shopping center in the northwestern city of Manchester, a police spokesman said.
The spokesman said anti-terrorism officers were investigating the incident, which the authorities suspect is an act of terrorism. The police evacuated the mall and stopped the train in Exchange Square in front of the mall.
The incident took place at Arndale Mall in the heart of Manchester shortly after 11 am (10 GMT). Photos on social media showed police using a stun gun while arresting the attacker.
Manchester Police official Ross Jackson told a news conference that the attacker was carrying a large knife.
"I was shocked by the Manchester incident," British Prime Minister Boris Johnson said on his Twitter account. "My heart is with the injured and all those affected."
Manchester has been the scene of the deadliest attack by militants in Britain in recent years, when a suicide bomber killed 22 people in May 2017 at the end of a concert by singer Ariana Grande in the Manchester Arena, not far from today's scene.