Violent protests erupt over train collision in Greece that killed 57

Anger over a same-track collision between two trains in Greece that killed nearly 60 people spilled onto the streets of Athens Sunday as a massive protest devolved into chaos when some demonstrators hurled Molotov cocktails at police who responded with tear gas and stun grenades.

Shouting "That crime won't be forgotten" and "Their policies cost human lives," protesters packed the heart of Greece's capital city, demanding the immediate bolstering of safety standards on the nation's rail system that they contend have eroded since the country's debt crisis from 2009 to 2018.

An estimated gathering of 12,000 protesters, most of them students and railway workers, filled Syntagma Square in the shadows of the Greek Parliament building and released black balloons into the sky to recognize those killed.

The peaceful protest escalated into chaos when a small group of demonstrators threw Molotov cocktails at police, according to Reuters. Video footage from the scene showed thousands of protesters dispersing from the square in all directions amidst a cloud of tear gas smoke.

Five people were arrested and seven police officers were injured when a group of more than 200 masked, black-clad individuals started throwing pieces of marble, rocks, bottles and firebombs at officers, according to the Athens Police Department.

Police officers responded to the incident with "limited use of the necessary, appropriate means" -- including tear gas and stun grenades, the police department said.

The clashes between police and protesters came as Pope Francis prayed for those killed and injured in the train collision.

"I pray for the dead, I am close to the injured and their relatives, and may Our Lady comfort them," Pope Francis said during his weekly Sunday service in St. Peter's Square at the Vatican.

The fervor of the demonstrations has grown since the deadly collision early Tuesday between a freight train and passenger train traveling on the same track 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.

About 350 crew and passengers, many of them students returning to college after a Greek Orthodox holiday break, were aboard the train that was moving at more than 100 mph when it plowed into the freight train, authorities said. Investigators blamed the collision on human error and said the two trains were running on the same line for 12 minutes, or a distance of about 11 miles, when the head-on crash occurred.

As of Saturday, the death toll from the crash had climbed to 57, authorities said. At least 80 people were injured.

In the aftermath of the crash, railway workers have staged job walkouts to protest cost-cutting on rail infrastructure they say is jeopardizing them and the public.

On Sunday, Greek Prime Minister Kyriakos Mitsotakis apologized to his country in a Facebook post.

"As prime minister, I owe everyone, but most of all the relatives of the victims, an apology," wrote Mitsotakis, who was elected in July 2019. "Justice will very fast investigate the tragedy and determine liabilities."

A station master in the city of Larissa, which is near the crash site, was arrested and charged with endangering lives and disrupting public transport. During a hearing Sunday before a magistrate judge, an attorney for the station master, whose name has not been made public, was granted more time to respond to the charges. The hearing was rescheduled for Saturday.

The station master's lawyer, Stefanos Pantzartzidis, said Sunday that his client has been ordered to be temporarily held in custody as the investigation continues.

"The accused said everything, he told the truth, he was devastated," Pantzartzidis said. "He said exactly what happened without fear that his words would make him bear more responsibility. If from what he said there is evidence that constitutes criminal offenses against him, it is something that justice will decide."

Unions for the railway workers have cited numerous safety deficiencies with the railway network, including previous problems arising from its signaling system and its insufficient surveillance system. The unions are demanding the government come up with a speedy timetable for reforming safety protocols.

In his Facebook statement Sunday, Mitsotakis said had there been a remote surveillance system in place throughout the rail network "it would have been, in practice, impossible for the accident to happen."

Mitsotakis announced his administration would seek help from the European Commission and other countries to bolster Greece's rail safety.

ABC News' Will Gretsky contributed to this report.