Two commuter trains in Warsaw have collided, injuring two people and raising questions about how they ended up on the same track.

The accident Wednesday comes nearly three months after a head-on collision of two trains in southern Poland killed 16 people. That disaster raised questions about the safety of train travel in Poland as the country prepares to co-host the European football championship next month.

Prosecutors said they opened an investigation into the accident, which occurred in the early morning in the capital's eastern Praga neighborhood. No cause was yet given.

The trains were apparently not traveling at great speed because photos from the scene showed them nose-to-nose on the track with only slight damage. One person was hospitalized and the other lightly injured.