[Updated at 11:35 p.m. ET] A train packed with rush-hour commuters plowed head-on into a barrier at a Buenos Aires station Wednesday morning, killing 50 people and injuring hundreds more, officials in Argentina said.

The train failed to stop as it should have, and slammed into the barrier at Once station at Plaza Miserere shortly after 8:30 a.m. local time, rail service owner Buenos Aires Trains said.

Video of the crash aired by Argentina TV station C5N shows people waiting on a platform as the train’s front section passes them and the camera. The train then comes to a violent halt, apparently because the front section hit the barrier farther down the track.

The crash caused the train’s second section to be pushed 6 meters into the first section, Transportation Secretary Juan Pablo Schiavi said, according to the Buenos Aires Herald. (See animated simulation of wreck from C5N)

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Other video from the scene showed rescuers prying open windows of the twisted train to reach trapped passengers. Crews carried bleeding victims on stretchers through the busy station; some victims were taken to area hospitals by helicopter.

Argentina’s president declared a two-day period of mourning.

“The government and people of Argentina give their solidarity and weigh the pain felt by the families of the victims,” President Cristina Fernandez de Kirchner said in a statement declaring the mourning period. Memorials will be held outside Argentina’s Government House and Olivos, the presidential residence, the state news agency Telam reported.

“Never in my life had I seen anything like this,” Schiavi told reporters hours after the accident.

Shaken passengers told reporters the crash sounded like a bomb blast.

“Suddenly I heard a bang, and many people fell on top of me. I think I had more than 10 people above me. I got out as quickly as I could,” a passenger named Esteban told state news agency Telam. “I only saw injured people and heard screams.”

Another passenger, identified only as Fabian, said he “flew 15 (meters) forward due to the impact,” the Buenos Aires Herald reported.

“I had people piled on top of me. None of us could move,” Fabian said, according to the Herald.

Another passenger told C5N that shortly before impact, when passengers noticed the train wasn’t stopping, some started to shout to others that they should run to the back.

The first two cars of the train – crammed with commuters – were most affected by the crash.

Passengers emerged bruised, some with serious injuries, Schiavi said. More than 460 were hospitalized.

The crash injured more than 600 people, the state-run Telam news agency reported.

Family members flooded local hospitals, clamoring for information about missing loved ones.

Officials were investigating the crash, which was one of the nation’s worst in decades.

They will use GPS data, security camera footage, audio recordings from the driver’s cabin and maintenance records in their investigation, Schiavi said.

The train stopped at other stations on its route, and data shows that it slowed down as it approached the Once station, Schiavi said.

“It stopped 14 times, and the last time, it didn’t stop,” he said.

The packed train was traveling at 26 kilometers per hour (16 mph) when it entered the station, he said.

“We do not know what happened in the last 40 meters,” he said.

The train’s 28-year-old driver had just started his shift and had a good record, the transportation minister said.

Earlier Wednesday, Schiavi said authorities believed there were problems with the train’s brakes that caused it to smash into a barrier at the station.

Buenos Aires Trains, which runs the rail service, said it was cooperating with the federal investigation.

“The company sends its condolences to the family members of the deceased passengers and remains very concerned about the health of all the injured people,” the firm said in a statement.

Wednesday’s crash was among the worst in Argentina’s history, Telam reported.

In 1970, 200 people died when two trains crashed north of Buenos Aires.

Eight years later, 56 people were killed when a train hit a truck in Argentina’s Santa Fe province, the state news agency reported.

Last September, a crash involving two passenger trains and a bus in Buenos Aires killed at least 11 people.