Residents have described the moments after a Croydon tram derailed killing five and injuring dozens.
People living nearby told of hearing a loud bang and seeing the injured being carried away on stretchers in the wake of the incident, which happened shortly after 6.10am on Wednesday.
Accident investigators are probing how the derailment happened. It is believed to be the first tram crash involving fatalities on board since 1959, when two women passengers and the driver died after a tram caught fire in Shettleston Road, Glasgow, following a collision with a lorry.
Adil Salahi, whose property overlooks the track, said the noise he heard was "sudden".
The 76-year-old said: "It was about 6.10am or 6.15am 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."
Sue Patel, who lives near the station, said: "I heard a noise at around 6 o'clock and I thought maybe it was a car or something. But then I saw there were helicopters."
She described the sound as "very loud" and a "very big bang".
Ms Patel, who said she regularly takes the tram line, said: "There's quite a big bend. You come through the tunnel and there's quite a sharp bend."
The tram appeared to have derailed at a point where the track branches. Liam Lehane, from the London Ambulance Service, described many of those hurt as "walking wounded" but said others suffered serious injuries.
Here's Simon Harris' report from lunchtime:
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."
The other 31 casualties were taken to Croydon University Hospital. Croydon Health Services NHS Trust said: "Our staff are currently triaging and caring for them so we would ask members of the public with more minor routine ailments to consider going to the local walk-in centre or their GP if possible."
Transport for London said the line is suspended between Reeves Corner and Addington Village/Harrington Road and is likely to remain closed for the rest of the day.
Mike Brown, London's Transport Commissioner, said: "All of our thoughts are with those who sadly lost their lives in this incident, those who were injured and the families of those affected.
"We are working closely with the emergency services on site and will continue to work with them during the investigation into what happened." London's only tram network operates in the south of the capital, from Wimbledon to Beckenham Junction, Elmers End and New Addington, via Croydon.
More than 27 million passengers used the service in 2015/16. The system uses a combination of on-street and segregated running for the 17 miles (27km) of track.
- Anyone concerned about loved ones can call the Casualty Bureau on 0800 056 0154.