Buenos Aires provincial governor Daniel Scioli told reporters that at least 14 wounded passengers were in serious conditions.

Earlier reports put the casualties at three dead and 31 injuried.

The tragedy occurred shortly before 9 p.m. local time in San Miguel, some 35 km northeast of the capital, when a long-distance train crushed a local train from behind.

A local police spokesman called the incident "catastrophic."

Firefighters, police, sanitary and medical workers have been working hard at the site to normalize the situation as quickly as possible.

An investigation has been underway to determine whether the incident was caused by a mechanical failure or a human error.

This was the second train collision in the past two months in Argentina. At least 51 people were wounded in the previous incident in a district in the capital city on December 31 last year.