At least 57 dead, dozens more injured in Greek train derailment

At least 57 people were killed and more than 80 others were injured in a head-on collision between a freight train and a passenger train in Greece late Tuesday, which officials said was mainly due to human error.

The crash occurred shortly before midnight in the town of Tempi along the Athens-Thessaloniki route at the entrance to the Vale of Tempe, a tree-lined gorge that separates the northern Greek regions of Thessaly and Macedonia. The two trains were running toward each other on the same track and the force of the high-speed collision derailed multiple cars, with some bursting into flames, according to Greece's Hellenic Fire Service.

The passenger train was traveling at a speed of about 103 miles per hour when it collided with the freight train, according to the Hellenic Fire Service. Greek state TV reported that the two trains were running on the same line for 12 minutes, or a distance of about 11 miles.

Greek Prime Minister Kyriakos Mitsotakis said Wednesday that the incident was "mainly due to tragic human error."

About 350 people were on board the northbound passenger train, which was traveling from Athens to Thessaloniki, according to the Greek rail operator Hellenic Train.

Roubini Leontari, chief coroner of the general hospital in the nearby city of Larissa, told Greek state TV that the majority of those killed were between the ages of 20 and 30 years old

At least 150 firefighters, including some from specialized units, and 40 ambulances responded to the scene with the assistance of 32 police officers and 15 patrol vehicles, according to the Hellenic Fire Service. The next morning, rescuers were still searching for survivors in the smoking wreckage, using cranes to lift the derailed carriages. Their efforts were initially focused on the first two cars, which had "overturned" and were "the most difficult to extricate," a Hellenic Fire Service spokesperson said in a statement early Wednesday.

The impact of the collision left the passenger train's restaurant car on top of two other cars. A blaze broke out in that carriage, with temperatures reaching as high as 1,300 degrees Celsius (2,372 degrees Fahrenheit), which "makes it difficult to identify the people inside," the Hellenic Fire Service spokesperson said in a statement on Wednesday afternoon.

The search and rescue operation at the site of the train collision will continue overnight into Thursday, according to the Hellenic Fire Service. Rescuers "will continue" the search "until the last stone is turned," a Hellenic Fire Service spokesperson said in a statement Wednesday evening.

A 59-year-old Greek citizen has been arrested in connection with the ongoing investigation into the deadly crash, according to Greece's Hellenic Police.

Meanwhile, authorities are still working to identify the dead, whose bodies were taken to the general hospital in the nearby city of Larissa, a Hellenic Police spokesperson said in a statement on Wednesday afternoon.

As for the injured, 48 remain hospitalized, including six in critical condition, while the rest have been treated and released, the Hellenic Fire Service said Thursday.

The Greek government has declared three days of national mourning in the wake of the tragedy.

Greek Prime Minister Mitsotakis said in a video statement on Wednesday that the government "will stand by the families of the victims" and "work so that this 'never again' that I heard in Larissa will not be a hollow word."

U.S. Department of State spokesperson Ned Price offered condolences to the people of Greece during Wednesday's press briefing in Washington, D.C.

"As we continue to see the death toll rise, I want to offer our sincere condolences to the people of Greece for the tragic loss of life in the train collision that happened overnight in the town of Tempi," Price said. "The United States stands with our friend Greece, and we commend the incredible dedication of first responders who are working tirelessly to save lives and attend to the injured."

U.S. Secretary of State Antony Blinken spoke with Greek Foreign Minister Nikolaos Dendias on Wednesday, extending condolences and said the United States stands with the people of Greece.

Greek Transport Minister Kostas Karamanlis announced his resignation on Wednesday after visiting the crash site in Tempi, saying he felt it was his "duty" to do so "as a minimum sign of respect" to the victims.

"When something this tragic happens, it is impossible to go on as if it didn't happen," Karamanlis wrote in a post on Facebook. "This is called political responsibility."

Mitsotakis said he has appointed a new interim transport minister, George Gerapetritis, to hold the office until national elections. The prime minister asked Gerapetritis to establish an "independent and non-partisan committee of experts" to investigate the cause of the accident and investigate the "long-standing delays" in the implementation of railway projects.

Meanwhile, Mitsotakis said two rail executives have resigned: Spyros Pateras, president of the Hellenic Railways Association, and Christos Vinis, president and managing director of the national railway subsidiary ERGOSE.

ABC News' Ellie Kaufman and Daphne Tolis contributed to this report.