Two people were injured when a train crashed through buffers at a station.
The incident involved a London Overground service at Enfield Town station, north London, during rush hour on Tuesday morning.
Images posted on social media show the train remained upright but came off the tracks and stopped just short of hitting a station building.
London Fire Brigade said around 50 people were evacuated from the eight-carriage train by Transport for London (TfL) and station staff.
The train driver is being “treated for shock,” Network Rail said.
A British Transport Police spokeswoman said the driver and another person were “checked over by paramedics at the scene.”
She added, “As is routine, the driver has been breathalysed and blew negative.”
Rory O’Neill, TfL’s general manager for London Overground, described the incident as “a low-speed collision with a buffer.”
He said, “There will be a full investigation to establish how this happened.”
A London Ambulance Service spokeswoman said: “We were called at 8:16 a.m. this morning to reports of a train derailed at Enfield Town railway station, Enfield.
“We sent a number of resources to the scene: one ambulance crew, an emergency planning officer, a clinical team manager, two incident response officers, medics in cars, and our hazardous area response team.
“Two people were assessed at the scene for minor injuries, but they were not taken to hospital.”
London Fire Brigade station commander Jim O’Neill, who was at the scene, said: “The train had hit the buffers at the station, which is at the end of the line, and gone up over the top of them.
“Firefighters carried out a systematic search of the train to ensure there were no further people on board.
“Crews assisted station staff to make the scene safe and a recovery operation will now be carried out.”
Three fire engines and two fire rescue units were sent to the scene.
A worker from a nearby postal sorting office said he was “shocked” by the sight of the crashed train.
Gary Spencer told the PA news agency that dozens of emergency services vehicles were outside the station.
“[There was] initially some shock but more importantly [I was hoping] that there were no casualties,” he said.
“I have never known a train to fail stopping at the end of the line … if the metal steel was not behind the buffer I’m confident the train would have damaged the building.
“The situation seemed very much in control.”
Rail regulator the Office of Rail and Road (ORR) said, “We’re aware of an incident at Enfield Town railway station and we are sending two ORR safety inspectors to assist emergency services and help establish the full circumstances surrounding this incident.”
TfL, which controls the London Overground network, said services were suspended from Edmonton Green to Enfield Town “while we deal with an operating incident at Enfield Town.”
By Neil Lancefield