LONDON — A passenger train derailed Thursday in southern England, leaving at least three cars flipped on their sides. Aerial footage showed firefighters and paramedics attending to passengers in a field next to the derailed train, with several ambulances and three helicopters standing by. There were no immediate official reports of injuries, though one passenger said he saw people who were bleeding. The Southern Rail train from Victoria station in London to Eastbourne derailed outside the tourist town of Lewes, the rail line and Network Rail said in a joint statement. Passenger Rob Bradley said the train began rocking as it picked up speed and the carriage he was riding in with his 6-year-old daughter jumped upward and the brakes immediately engaged. “Everything got thrown forward. My laptop, my AirPods, our bags,” Bradley told the BBC. “The train kind of skidded for quite a while before it stopped and only then when we turned around did we see that the whole back of the train — literally where we were sat — was open and there was smoke and dust pouring into the carriage.” He could then see the car behind had flipped on its side and slid down an embankment into a lower field. Bradley said he and his daughter were fine but he could see other passengers in one of the flipped cars with blood on their heads and clothing. Another passenger told him they had been cut when a window shattered. “Deeply concerned of reports of a derailment involving a Southern train,” Transport Secretary Heidi Alexander said on X. “Grateful to emergency services who are on the scene supporting those impacted.”