AFP BUENOS AIRES A PACKED commuter train slammed into a retaining wall at a railway terminus in Buenos Aires during rush hour on Wednesday, leaving at least 49 dead, 550 injured, and dozens trapped in the wreckage.

“The train was full and the impact was tremendous,” a passenger identified only as Ezequiel told local television, adding that medics at the scene appeared overwhelmed by the scale of the disaster.

Witnesses said passengers were hurled on top of each other and knocked to the floor “in the blink of an eye,” some losing consciousness and others seriously injured.

“Unfortunately, we must report that there are 49 dead in the accident,” including a child, police spokesman Nestor Rodriguez told a news conference.

Civil defense officials said at least 550 people were injured in the crash, which witnesses said occurred after the train’s breaks failed as it was arriving at a station on the western outskirts of Buenos Aires.

The toll surpassed the city’s last major rail disaster just five months ago when two trains and bus collided during rush hour, killing 11 people and injuring more than 200.

A dozen ambulances were dispatched to the scene, and officials said many passengers had suffered multiple fractures and abrasions. At least 30 people were trapped in the twisted wreckage of the first and second cars of the train, Alberto Crescenti, the head of the city’s emergency services office, said.

Transportation Secretary Juan Pablo Schiavi said the train entered the station at a speed of 20 kilometers an hour, and failed to stop, crashing into a retaining wall at the end of the track.

“It was a very serious accident,” he said at a news conference.

“Cars piled up on top of each other and one them went six meters inside another car.” “People suffered contusions, but there are much more complex cases involving traumas of the thorax. There are people trapped alive in the cars.” Firefighters and rescue workers had to break through skylights in the train’s roofs to open a path to those trapped inside.“I felt the explosion of the crash. It was very loud. The train did not brake, I saw people hurt in their necks, arms, legs,” said Pedro Fuentes, a passenger. Another passenger, who identified herself as Myriam, said she was with her two children, ages six and four.

“In a blink of an eye we were on the floor. I don’t know how we got out. The door crashed in one me, and I covered the girl.” The train’s driver was injured but rescue workers pried him loose from the wreckage of his cabin. Local television showed images of him and several people being carried away on stretchers.

An investigation into the crash has been opened, but an employee with the rail line’s maintenance department, Monica Slotauer, said “the brakes failed and this is the result of a lack of investment.” The Sarmiento rail line, which links the center of Buenos Aires to a densely populated suburb 70 kilometers to the west of the city, uses rolling stock acquired in the 1960s.

The accident occurred just five months after the Argentine capital was shocked by another rush hour transit disaster, that one involving a collision between two trains and a bus.

That accident in September killed 11 people and injured more 200. The region’s transit system has been plagued with serious accidents in recent years. In March 2008, 18 people were killed and 47 injured when a bus was hit by a train in Dolores, 212 kilometers south of Buenos Aires.

Argentina’s deadliest train tragedy was in 1970, an accident that killed 200 people in north Buenos Aires.