The train slammed into the barrier at the end of the platform at the Once station during the morning rush hour.
Eyewitnesses said the train was travelling fast. The train had hit the barrier at about 12mph (20km/h), destroying the front of the engine and crunching the carriages behind it, Schiavi said. One of the carriages was driven nearly 20 feet into the next, he said. Dozens of people remain trapped.
Emergency workers are working to extract dozens of people trapped inside the first car, said health official Alberto Crescenti.
Survivors told local media that many people had been injured in a jumble of metal and glass. Some suffered fractures and other serious injuries. This latest accident is Argentina's worst train crash since 1970.
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