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.

Andy Rowe from London Fire Brigade said firefighters had to release a significant number of people.

"We had to undertake cutting and lifting operations and will continue to support our colleagues in the investigative branches and the police," he added.

People who had been advised to go to the church should now go to Bernard Weatherill House. 

A spokesperson for Croydon Health Services NHS Trust said: “Following the incident of a derailed tram in Croydon this morning, a number of people have been brought to our Emergency Department for care and treatment.

“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." 

In a press conference moments ago in Croydon, Assistant Chief Constable Robin Smith of the BTP said colleagues were working with fire, ambulance and police to currently free two people still trapped.

He said a number of victims had been taken to hospital and there had been "some loss of life" but it was "too early to confirm numbers".

He said the focus was on recovery efforts  and contacts will soon be made available for concerned family and friends.

A spokesman for London Ambulance Service said it had transported over 50 patients to St Georges and Croydon hospitals.

"Most of those patients were walking wounded, but there are however some with serious injuries," he said.

British Transport Police (BTP) say there have been deaths on the tram crash in Croydon this morning but can't say how many. 

They confirm that two people are still trapped and that over 50 patients have been treated in hospital. 

Image source, Getty Images

There has been "some loss of life" in this morning's tram derailment in Croydon, say the British Transport Police.

The BTP held a press conference in Clyde Road alongside London Fire Brigade and the London Ambulance Service.

More to follow.

Resident Margaret Hinder emailed BBC London Live following this morning's tram derailment to describe the atmosphere in the area.

"I'm about half a mile from the site of the tram derailment. It is almost eerily quiet.  We normally get a steady stream of commuters and school run traffic in the mornings. 

"Today there is almost total absence of traffic noise: just emergency sirens every so often.Thoughts with those injured, of course, and with the two still reportedly trapped."

Image source, Getty Images

Eleanor Elliott sent in this photograph of the scene. 

Image source, Eleanor Elliott

A spokesman for nearby St George's Hospital said: “Following an overturned tram incident in Croydon early this morning, 20 people have been brought to St George’s Hospital for treatment. 

"Of these 20 patients, four are seriously injured. All patients are being cared for by our clinical teams. We will share further updates in due course.”

Tom Edwards
Transport Correspondent, BBC London

It is a major incident.

Rail safety investigators are en-route.

As to what happened here, we don’t know. There are four lines here that converge further up that would perhaps indicate that points were to blame.

There was also torrential rain earlier perhaps that had something to do with it – but this is complete speculation.

The whole area has come to a standstill. No trams are coming or going from east Croydon station.

The mood is extremely sombre.

Image source, PA

Adil Salahi, whose property overlooks the track, said the noise he heard was "sudden". 

The 76-year-old said: "It was about 6.10/6.15 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."

Image source, Getty Images

Two people are trapped and more than 50 people have been injured after a tram derailed in south London. 

Scores of emergency services are at the scene in Croydon where two carriages overturned at about 06:10 today.

Images from the scene show the vehicle on its side next to an underpass near the Sandilands tram stop. 

The tram appeared to have derailed at a point at which the track branches. People living nearby told of hearing a loud noise and seeing the injured being carried off on stretchers.  

London Ambulance Service said: "We have treated a number of patients and over 50 have been taken to hospital." 

Image source, PA

Accident investigators have gone to the scene to begin gathering evidence, the Rail Accident Investigation Branch said. 

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 of track.