At least 32 people have died and dozens more injured after two trains collided in northern Greece, emergency services say.
A train said to be carrying around 350 passengers hit a freight train travelling in the opposite direction near the city of Larissa late on Tuesday night.
Rescuers have been working through the night to find survivors, the fire service said.
The cause of the crash is not known.
The passenger train had been travelling from Athens to the northern city of Thessaloniki when it crashed head-on with the other train, leading to a fire in at least one of the carriages.
One survivor described how the carriage he was in was engulfed in flames as it rolled over following the crash.
"We heard a big bang," passenger Stergios Minenis was quoted as saying by Reuters news agency.
"It was a nightmarish 10 seconds. We were turning over in the carriage until we fell on our sides and until the commotion stopped. Then there was panic. Cables, fire. The fire was immediate. As we were turning over we were being burned. Fire was right and left," Mr Minenis said.
"For 10, 15 seconds it was chaos. Tumbling over, fires, cables hanging, broken windows, people screaming, people trapped."
Another passenger named Angelos Tsiamouras told local media the crash had felt like an earthquake.
"It was a very powerful collision," the regional governor of the Thessaly region, Kostas Agorastos, told state-run television.
"This is a terrible night... It's hard to describe the scene."
Footage of the collision's aftermath showed thick plumes of smoke rising from derailed carriages.
At least one of them was completely crushed.
Around 150 firefighters and 40 ambulances were at the scene, the fire service said.
Conditions for rescue workers were "very difficult" because of "the severity of the collision", fire service spokesman Vassilis Varthakoyiannis told reporters.
"I've never seen anything like this in my entire life. It's tragic. Five hours later, we are finding bodies," an exhausted rescuer emerging from the wreckage told AFP news agency.
"We are living through a tragedy. We are pulling out people alive, injured... there are dead. We are going to be here all night, until we finish, until we find the last person," another volunteer rescue worker told ERT state broadcaster in comments cited by Reuters.