Five people were injured after an explosion at a London Tube station thought to have been caused by a battery short circuit.
Officers were called to reports of people running at Southgate Tube station shortly after 7pm on Tuesday.
A man on a “packed” escalator said some people had been “trampled” in the commotion.
London Ambulance Service said two people had been taken to hospital and three others were treated at the scene in north London for minor injuries.
A spokeswoman said: “We have treated three patients at the scene for minor injuries and have taken two people to hospital.”
The Metropolitan Police said: “It appears at this stage that the cause of the explosion was a battery short circuit.
“The Met Police and BTP (British Transport Police) are working together to establish the full facts.”
James Ayton, 34, from Southgate, was on the “packed” escalator when he saw a “quick burst” of flames at the top and said everyone “legged it”.
He said there had been a “very rapid whooshing sound”.
He added: “A few people got trampled on on the escalator. There was screaming.
“An old woman got trampled on. I had to carry a woman up the stairs. I think she was in shock to be honest. She couldn’t walk, shaking.”
Mayor of London Sadiq Khan praised emergency services for “a swift and professional response” to the incident.
British Transport Police (BTP) confirmed the incident was not believed to be terror-related.