Two people were seriously injured Thursday afternoon when a passenger train derailed in East Sussex, England, the British Transport Police said in a statement.
Nine other people suffered less serious injuries in the incident, in which three of the train’s eight carriages left the tracks and flipped onto their sides. Officials said people who were trapped in those cars had since been evacuated.
Some of the injured were treated at the scene, while others were taken to local hospitals, officials said.
Pictures of train cars lying on their side, with emergency workers and others standing on the top of the carriages were being shared online.
“We’ve declared a major incident, and a significant emergency service response is ongoing at the scene,” said Ian Drummond-Smith, the assistant chief constable at the department. “But all passengers on the train have now been safely evacuated from the service.”
It was unclear what caused the accident, though pictures from the scene showed bent and twisted rails where the three train cars apparently skidded off the track.
Heidi Alexander, the British transport secretary, said in a statement on social media that she was “deeply concerned of reports of a derailment.”
Aerial video footage from a BBC helicopter showed three of the eight train cars lying on their side, with a fourth partly derailed. The other four cars appeared to be still upright on the tracks.
Rob Bradley, a passenger, told the BBC that the journey with his daughter had seemed normal until they felt the train speeding up abruptly.
The train “then started to rock, and at that point I knew something was very strange, and then our carriage actually jumped vertically upward and we could tell it was a derailment,” Mr. Bradley said. “The emergency brakes then went on, the train and everything got thrown forward.”
Mr. Bradley said he and his daughter were in one of the carriages that did not tip over. But he said he saw some people with blood on their clothes as he evacuated the train.
Southern Railway, the company that operates the train, confirmed the incident in a statement: “A train has derailed in the area between Haywards Heath and Lewes. Emergency services are making their way to the scene, and we are working out the impact this will have on our network.”
The company added, “If you are traveling between London and the East Coast, we advise against traveling.”
The derailment took place on a section of a rail line between London and southeastern England. Thursday was the hottest day of the year so far in Britain, with temperatures in one part of London reaching 38 degrees Celsius, or around 100 Fahrenheit.
The Rail Accident Investigation Branch, an independent government agency, said it would begin an investigation.
In a statement on social media, the agency said that it was “deploying a team of inspectors to the site of a passenger train derailment near to Lewes, East Sussex, to begin gathering evidence.”
Mr. Drummond-Smith, of the British Transport Police, said his department was “supporting the Rail Accident Investigation Branch to establish exactly what’s happened. We’ll provide further information as soon as we are able.”
