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 36 people were killed 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.

It added that 66 people were being treated for their injuries in hospital, with six in intensive care units.

The two trains involved in the fatal collision were traveling on the same track for many kilometers before the incident occurred, state-owned public broadcaster ERT reported Wednesday. The passenger train had changed lanes and switched to a cargo track before it collided head-on with a freight train, according to ERT.

The process of identifying victims has also begun, Greek Health Minister Thanos Plevris said early on Wednesday.

Speaking outside the hospital in Larissa, Plevris said: “As you understand this is a terrifying process for parents and relatives who are here. We will help them as much as we can.”

He said there were “some difficulties” in the identification process, but added that, “Those injured are in relatively good condition.”

Greek Prime Minister Kyriakos Mitsotakis is heading to the scene of the collision, his office confirmed to CNN Wednesday.

“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, with the focus on the first carriages of the passenger train, the Greek Fire Service said. The death toll is expected to rise.

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 earlier that 194 passengers had been taken safely to Thessaloniki and 20 people transferred by bus to the city of Larissa.

At least 150 firefighters including special rescue units with 17 vehicles and 30 ambulances were involved in the rescue operation, Varthakogiannis added.

“All the actions of the firefighters operating on the scene are focused on the first three carriages of the train,” he said. “The crane vehicles are creating the conditions to access and fully check the interior of the carriages.”

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.”

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.

Condolences have begun pouring in from across the world. Writing on Twitter, French Foreign Minister Catherine Colonna said: “Sad thoughts after the terrible train accident near Larissa in Greece … my heart goes out to the people of Greece and I express my sincere condolences to the victims and their families.”

“My thoughts are with the people of Greece,” said European Commission President Ursula von der Leyen.

“The whole of Europe is mourning with you. I also wish for a speedy recovery for all the injured.”

Charles Michel, the president of the European Council, tweeted on Wednesday: “My thoughts are with the people of Greece this morning.”