More than 40 people have died and at least 550 people have been injured after a train crashed into a platform at a Buenos Aires station.

Local reporters say they saw 12 bodies removed from the wreckage, with many more still inside.

"There are fatalities," said Alberto Crescenti, the city's emergency medical director, speaking to Associated Press.

Transport Secretary Juan Pablo Schiav told reporters at the station that the commuter train had hit the barrier at about 12mph (20km/h), according to the BBC. At least 30 people are still believed to be trapped inside the first carriage.

One carriage is reported to have driven nearly 20 feet (six meters) into the next following the crash.

"The train was full and the impact was tremendous," a passenger identified only as Ezequiel told local television, stating that medics at the scene were overwhelmed.

It is not yet known what caused the crash.

"This machine left the shop yesterday and the brakes worked well. From what we know, it braked without problems at previous stations. At this point I don't want to speculate about the causes," Ruben Sobrero, union chief on the Sarmiento line, told Radio La Red.