A busy passenger train derailed near Lewes, a market town in the county of East Sussex in southeast England, on Thursday afternoon, injuring 20 people and prompting emergency services to declare a major incident. Two passengers were taken to a major trauma centre with severe injuries, while 18 others sustained less serious wounds. All approximately 150 people on board have since been safely evacuated.

The train, operated by Southern Rail — a service connecting areas south of London to the capital — had departed from London Victoria station and was heading for the coastal town of Eastbourne when it veered off the tracks shortly before 4:00 pm local time. Aerial footage showed at least three carriages overturned at the scene, with paramedics, ambulances, and trauma helicopters deployed in large numbers. Deputy chief paramedic officer Michael Bradfield confirmed the range of injuries at a news briefing, noting that the two most seriously hurt had been transported to specialist care.

One passenger, who had been travelling with his six-year-old daughter, described a frightening sequence of events: the train had just picked up speed when it began to tilt. "It was clear the train was derailing," he told the BBC. "The emergency brake was applied and everything flew forward. The train slid for a while before it came to a stop. When we turned around, the back of the train was open — smoke and dust poured in, and we could see the fifth carriage was on its side." He and his daughter escaped unharmed, though he witnessed fellow passengers with head wounds and cuts.

The cause of the derailment has not yet been officially established. Network Rail's route director for Sussex, Lucy McAuliffe, said the company is working closely with the Rail Accident Investigation Branch, which has sent investigators to the site. A BBC reporter on the ground noted that some images appeared to show buckled track, raising the possibility that extreme heat may have played a role — rails are known to warp under very high temperatures, and Britain was experiencing an exceptionally warm day. Officials were careful to stress that the distortion could equally have been caused by the accident itself. Transport Secretary Heidi Alexander said she was "deeply concerned" by the incident.

Train services across a wide area have been severely disrupted, with Southern Rail urging passengers not to travel and halting all trains around Lewes. Stations in the area, including on routes between Brighton, Haywards Heath, Seaford, and Eastbourne, remain closed or affected. Train accidents — particularly fatal ones — are relatively rare in Britain, though the country experienced a fatal collision between two trains north of London in June of this year.