TEMPE, Greece >> Rescuers delved Wednesday through flattened, burned-out carriages for survivors and bodies after a passenger train and a freight train crashed head-on in central Greece overnight, killing at least 36 people and injuring scores.

Transport Minister Kostas Karamanlis resigned Wednesday, saying he felt it was his “duty” to step down “as a basic indication of respect for the memory of the people who died so unfairly.”

The cause of the crash near the Vale of Tempe, about 235 miles north of Athens, was not immediately clear, but the stationmaster in the nearby city of Larissa was arrested Wednesday. The police did not release his name. Another two people have been detained for questioning.

It’s unclear at what speed the two trains were traveling when they ran into each other just before midnight Tuesday, but state broadcaster ERT said it was more than 87 miles per hour.

Survivors said the impact threw several passengers through the windows of train cars. ERT quoted rescuers saying they found some victims’ bodies 100-130 feet from the impact site.

Stefanos Gogakos said it felt like an explosion, while from his rear carriage, flames could be seen at the front of the train.

“The glass in the windows shattered and fell on top of us,” he told ERT. “My head hit the roof of the carriage with a jolt. Some people started to climb out through the windows because there was smoke in the carriage. The doors were closed but in a few minutes train staff opened them and we got out.”

Multiple cars derailed and at least three burst into flames. On Wednesday, one carriage lay atop the crumpled remains of another two.

“Temperatures reached 1,300 degrees Celsius (2,372 Fahrenheit), which makes it even more difficult to identify the people who were in it,” fire service spokesperson Vassilis Varthakoyiannis said.

Many of the 350 people aboard the passenger train were students returning from Greece’s raucous Carnival, officials said. This year was the first time the three-day festival, which precedes Lent, was celebrated in full since the start of the pandemic in 2020.

Visiting the accident scene, Greek Prime Minister Kyriakos Mitsotakis said that the government must help the injured recover and identify the dead.

“I can guarantee one thing: We will find out the causes of this tragedy and we will do all that’s in our power so that something like this never happens again,” Mitsotakis said.

Greek President Katerina Sakellaropoulou broke off an official visit to Moldova to visit the scene, laying flowers beside the wreckage.

The government declared three days of national mourning from Wednesday, while flags flew at half-staff outside all European Commission buildings in Brussels.

Pope Francis offered his condolences to the families of the dead, in a message sent to the president of the Greek bishops conference on his behalf by the Vatican’s secretary of state,

The pontiff “sends the assurance of his prayers to everyone affected by this tragedy,” the message said.

On Wednesday, rescuers turned to cranes and other heavy machinery to start moving large pieces of the trains, revealing more bodies and dismembered remains. Officials said the army had been contacted to assist.

Rescuer Lazaros Sarianidis told state broadcaster ERT that crews were “very carefully” trying to disentangle steel, sheet metal and other material that was twisted together by the crash. “It will take a long time,” said Sarianidis.

Costas Agorastos, the regional governor of the Thessaly area, told Greece’s Skai Television that the two trains collided head on at high speed.

“Carriage one and two no longer exist, and the third has derailed,” he said.

The trains crashed just before the Vale of Tempe, a gorge that separates the regions of Thessaly and Macedonia.

“There were many big pieces of steel,” said Vassilis Polyzos, a local resident who said he was one of the first people on the scene. “The trains were completely destroyed, both passenger and freight trains.”

He said dazed and disoriented people were escaping out of the train’s rear cars as he arrived.

“People, naturally, were scared — very scared,” he said. “They were looking around, searching; they didn’t know where they were.”

Eight rail employees were among those killed in the crash, including the two drivers of the freight train and the two drivers of the passenger train, according to Greek Railroad Workers Union President Yannis Nitsas.

Greece’s firefighting service said some 66 people were hospitalized, including six in intensive care.

More than 200 people who were unharmed in the crash or suffered minor injuries were transported by bus to Thessaloniki, 130 kilometers (80 miles) to the north. Police took their names as they arrived, in an effort to track anyone who may be missing.

Barely able to hold back tears, Greece’s Transport Minister Kostas Karamanlis told reporters at the crash site that authorities would investigate “in all seriousness and complete transparency” the causes of the crash.

“We will do everything to investigate the causes and won’t leave anything to be swept under the carpet,” Karamanlis said.

A teenage survivor who did not give his name to reporters said that just before the crash he felt strong braking and saw sparks — then there was a sudden stop.

“Our carriage didn’t derail, but the ones in front did and were smashed,” he said, visibly shaken.

He added that the first car caught fire and that he used a bag to break the window of his car, the fourth, and escape.

Rail operator Hellenic Train said the northbound passenger train to Thessaloniki, Greece’s second-largest city, had about 350 passengers on board.

Hellenic Train is operated by Italy’s FS Group, which runs rail services in several European countries.

Patrick Quinn and David Rising contributed to this story from Bangkok. Gatopoulos reported from Athens.