(CNN) — Rescue workers are in a desperate search for survivors after a head-on collision between two trains in central Greece killed dozens of people and injured scores.

At least 29 people were killed and more than 85 injured when a passenger train carrying more than 350 people collided with a freight train on Tuesday evening, shortly before midnight, in Tempi, central Greece, near the city of Larissa, the Greek Fire Service said.

“We just heard a bang… the (train) car started spinning, before ending up sideways when we managed to exit,” one male passenger told Greek public broadcaster ERT.

“It was 10 nightmarish seconds with fire, you couldn’t see much from the smoke,” said a second passenger.

Recovery efforts are underway and the death toll is expected to rise, the Greek Fire Service said.

The passenger train had been traveling from the capital Athens to Thessaloniki, Greece’s second-largest city, which is renowned for its festivals and vibrant cultural life. The collision follows a nationwide carnival at the weekend which ended with a public holiday on Monday.

Images on Greece’s state-owned public broadcaster ERT showed plumes of thick smoke pouring out of toppled carriages and long lines of rescue vehicles next to them.

Meanwhile, rescue workers with torches searched carriages for survivors as paramedics led shell-shocked passengers from the scene.

The images also showed some surviving passengers arriving in Thessaloniki.

Greek Fire Service spokesman Vassilis Varthakogiannis said that 194 passengers had been taken safely to Thessaloniki.

At least 150 firefighters with 17 vehicles and 40 ambulances are involved in the rescue operation, he added.

The Greek railway company, Hellenic Train, said in a press release that there was “a head-on collision between two trains: a freight train and train IC 62 which had departed from Athens to Thessaloniki.”

Authorities said it is still not clear what led to the collision.

Hellenic Train, the main Greek railway company, was acquired by Ferrovie dello Stato Italiane in 2017 and is now fully controlled by Trenitalia. The company operates both passenger and freight transport. The main line on which daily connections are offered is Athens-Thessaloniki.