Several people were injured when a concrete mixer lorry fell from a bridge onto a train at Oxshott, Surrey.
The vehicle landed on coaches of the 1505 South West Trains passenger service from Guildford to London Waterloo at around 1530 GMT.
The lorry driver was trapped for a time in the wreckage, but has now been freed and taken to hospital.
A British Transport Police spokesman said his injuries were not life-threatening.
A total of 36 people were on the train. The five people injured in the accident were all in a stable condition.
The 38-year-old driver of the concrete-mixer was taken to St George's Hospital in Tooting.
"His injuries don't appear to be as serious as first thought and are not life-threatening," a spokesman said. "His condition will continue to be assessed overnight by hospital staff."
A 60-year-old passenger was also taken to St George's Hospital as a "precaution." The other injured passengers were treated at Epsom General Hospital in Surrey and the Royal Surrey County Hospital.
The lorry left the road at Warren Lane, a short distance from Oxshott railway station, crashing through a brick wall on a bridge above the busy commuter line.
It struck the third carriage from the back of the eight carriage train, punching a large hole in the metal roof.
Passenger Ade Joshua told BBC News: "In the carriage right next to us where the incident happened, there was a guy trapped with what looked like a broken back, so we were trying to console him as much as we could until the emergency services arrived.
"But we couldn't actually get through to the carriage because the door was blocked as that bit of the train collapsed."
Timi Raji, 18, who was in the carriage next to the one that was crushed, rushed to the adjoining door when the train ground to a halt following a loud bang.
He said: "The door was blocked but we could see someone was at the bottom of the carriage, trying to get out.
"The train had been crushed and the guy was trying to escape.
"He was on his stomach and we could only see his feet sticking out. My friends and I were trying to calm him down and talking to him."
Witness Nikki Karim works in a taxi office near to the crash site.
She said: "There's a lot of police at the station, there's a few minor casualties that are sat at the platform."
She added: "You don't expect this sort of thing to happen."
The incident took place on a branch line, and is unlikely to result in major disruption.
The bridge from which a lorry fell was assessed as safe in the nationwide checks made after the Selby rail disaster nearly 10 years ago.
The checks were ordered after a Land Rover came off the road and on to the East Coast Main Line in February 2001.