At least 40 people were killed and hundreds were injured when a commuter train rammed the wall at a station in Argentinean capital Buenos Aires on Wednesday.
The preliminary death toll was announced by local emergency services. Media spoke earlier about at least 550 injured and another 40 passengers blocked in the wreckage.
The incident took place on the first work day to follow a four-day summer carnival, a national holiday.
The nine-car train with some 1,000 passengers rammed the buffer stop at 26 kph, crushing the locomotive and the first three cars, a spokesman for the emergency services said. It remained unclear what caused the disaster.