49 killed as train slams into retaining wall in Buenos Aires Rescuers take wounded persons out of a carriage at the site of a train derailment in Buenos Aires. Telenoticiosa Americana / Xinhua / Zuma Press / MCT / February 22, 2012 By Andres D'Alessandro and Chris Kraul, Los Angeles Times February 22, 2012, 10:08 a.m. A commuter train went out of control and slammed into a retaining barrier in a central Buenos Aires train station during peak rush hour Wednesday morning, killing at least 49 people and injuring more than 500, federal police officials said. After impact, many cars pancaked or jumped the tracks, killing both passengers and people waiting at the station to board. No official cause of the accident had been determined by midday, but officials speculated that a brake or system failure or human error sent the train out of control. Police spokesman Nestor Rodriguez said the train was traveling about 15 mph and that the toll could have been much higher had it been traveling faster. The train that crashed was on the Sarmiento line that brings commuters to central Buenos Aires, the capital, from the western reaches of the metropolis. Three hours after the crash, rescue workers with the Emergency Medical Care System along with firefighters and police were working frantically to free trapped passengers and extract victims from the twisted and compacted wreckage of the train. Television coverage of the wreck showed scenes of anguish and desperation among people seeking news of friends and relatives on the train. Several hospitals were coping with treating the estimated 550 injured people. One passenger who identified himself only as Emanuel told the newspaper El Clarin that he was nearing the end of his commute to his job when he felt a strong impact, followed by passengers "falling on top of each other" and by desperate screams. Several members of a rail workers union said in TV interviews that the commuter train system had fallen into disrepair. Union spokesman Rubén Sobrero, however, told reporters that the train's braking system had been checked as recently as Tuesday night at the Castelar maintenance facility.