The driver of the tram in Croydon which derailed, killing several people and injuring dozens of others, has been arrested.
Emergency services are still working at the scene near Sandilands tram stop in Croydon to free people trapped, British Transport Police said.
More than 50 people were injured when the crowded rush-hour two-carriage tram tipped onto its side next to an underpass near the stop at around 6.10am on Wednesday.
Robin Smith assistant chief constable of BTP said: “It is too early for us to confirm numbers but we are working hard to assess the ongoing incident and we are continuing to focus on recovery efforts.”
He said: “A number of people have been taken to hospital with injuries and sadly it looks as though there has been some loss of life.
“It is too early for us to confirm numbers but we are working hard to assess the ongoing incident and we are continuing to focus on recovery efforts.”
Accident investigators have gone to the scene to probe how the derailment happened.
People living nearby told of hearing a loud noise and seeing the injured being carried away on stretchers.
The tram appeared to have derailed at a point where the track branches.
London Fire Brigade sent eight appliances and more than 70 firefighters to the scene in Addiscombe Road.
Croydon resident Hannah Collier, 23, said: “I heard a massive crash at about 6.15am, then heard shouting, then the emergency services arrived.
“They started bringing up the casualties, some very seriously injured. People were carried away on stretchers.”
Adil Salahi, whose property overlooks the track, said the noise he heard was “sudden”.
The 76-year-old said: “It was about 6.10 or 6.15 and because I was praying. I could not move and try to check what it is. I thought it was something in the garage doors. Then I thought it was some lorry.”
Transport for London said the line is suspended between Reeves Corner and Addington Village/Harrington Road.
British Transport Police said they are working to set up a number for friends and relatives to call but until then anyone with concerns is advised to call 101.
St George’s Hospital in Tooting, south-west London, is treating 20 people.
A spokesman said: “Of these 20 patients, four are seriously injured. All patients are being cared for by our clinical teams.”
Liam Lehane, from the London Ambulance Service, said a number of people were seriously injured.
He said: “We have transported over 50 patients to a number of hospitals.
“Most of those patients were walking wounded. But there are, however, a number of patients with serious injuries. We will continue to work on the scene with the other emergency services during the recovery operation.”