At least seven people were killed and more than 59 people were injured after a tram got derailed and overturned in south London’s Croydon town on Wednesday. The British Transport Police said the accident might have taken place because the driver of the tram fell asleep behind the wheel. He has been arrested on charges of manslaughter. However, the Rail Accident Investigation Branch said they were investigating a couple of factors that might have led to the incident, including the possibility that the tram was travelling at a high speed while negotiating a sharp bend.

“Our officers will continue to work tirelessly throughout the evening to formally identify them and provide care and support for their families,” said Deputy Chief Constable Adrian Hanstock. London Ambulance Service said 51 others had been taken to two hospitals, of whom eight people had sustained serious injuries, and BBC reported.

Martin Bamford, 30, who was in the two-carriage tram, said, “Everyone just literally went flying. People were screaming and there was “blood everywhere.” Andy Smith, who was standing near the site of accident when it took place, said, "I heard what sounded like a screeching noise, then a bang. [I looked] down the track and I saw carnage.”

Croydon Central MP Gavin Barwell said "It’s been a very shocking day for the whole community here. Thousands of people use these every day.” He said the tram ran on a “modern environmentally-friendly transport system” and that it has had a great safety record. This is the first time since 1959 that a tram accident of this scale has taken place in the country. The mishap in 1959 left two passengers and the driver dead.

Mike Brown, commissioner of Transport for London, said: “Clearly something has gone catastrophically wrong and we will work tirelessly and quickly to establish the cause.” British Prime Minister Theresa May offered her condolences and prayers for the victims and their families. City mayor Sadiq Khan visited the accident site.