Five people were gravely injured Monday when two commuter trains collided near the Austrian capital, ORF television said.

The accident occurred around 8:45 a.m. when two trains full of passengers crashed head-on for reasons still unknown, but that were possibly related to a malfunctioning railroad switch or a misunderstanding in giving the trains the go-ahead to pass.

Two passengers suffered life-threatening injuries.

An intense emergency management operation, which took two hours and included some 25 vehicles and two helicopters, carried out the rescue work and the removal of passengers.

The crash occurred in the district of Penzing at a point on the line that has only one track for all train traffic. EFE