Six men and one woman died in Wednesday's tram crash in Croydon. A police spokesman said officers were working with the coroner to identify the victims.
The tram driver, a 42-year-old man, from Beckenham, was released on bail after being arrested on suspicion of manslaughter. Investigators said the tram was travelling at a "significantly higher speed than is permitted" and are probing whether the driver had fallen asleep.
British Transport Police officers and forensic investigators remain at the scene, where more than 50 people were injured when the vehicle left the track during the morning rush hour.
Three underwent surgery at St George's Hospital, Tooting, on Wednesday. Some 17 other patients have since been discharged from the hospital.
Thirty-eight of those injured were treated at Croydon University Hospital. One remained in the hospital overnight but it was hoped they would be able to go home on Thursday.
Dane Chinnery, a 19-year-old Crystal Palace fan described as a "friendly, genuine lad", was among those killed.
Crystal Palace issued a statement on behalf of manager Alan Pardew, chairman Steve Parish, the players and club staff, offering their "sincere condolences to the families of those who lost their lives".
The tram was travelling from New Addington to Wimbledon via Croydon when the accident happened at 6.10am. Scenes after the crash were described as "total carnage" after the two-carriage tram tipped over in heavy rain next to an underpass.
Survivors rescued from the wreckage said the tram failed to brake in its usual place at a bend on the track after speeding up. One said the driver told them he thought he had "blacked out".
Martin Bamford, 30, from Croydon, said he recalled the tram speeding up, adding: "Everyone just literally went flying."
Speaking outside Croydon University Hospital, where he was being treated for fractured or broken ribs, he said people were screaming and there was "blood everywhere", describing the scene as "like something out of a film".
He added: "There was a woman that was on top of me... I don't think she made it at all. She wasn't responsive. There was blood everywhere."
London Mayor Sadiq Khan, who visited the crash scene on Wednesday, warned the death toll could rise. Saying that the Union flag had been flying at half-mast at City Hall, he added: "My team continues to work with Croydon Council to find the best way to provide immediate help and support for those most affected.
"Investigations into what caused this tragic incident continue, and it is vital that we learn the lessons as quickly as possible to prevent anything like this from happening again."
Initial findings of the Rail Accident Investigation Branch show the tram came off the tracks as it was negotiating a "sharp, left-hand curve" with a speed limit of 12mph. A spokesman said: "Initial indications suggest that the tram was travelling at a significantly higher speed than is permitted."
Dozens of floral tributes have been left near the scene by well-wishers.