VIENNA — Two trains packed with morning commuters crashed head-on Monday on Vienna’s outskirts after a state railway employee apparently forgot to activate a signal. Railway officials said 41 people were injured, five seriously.

A statement from OBB, Austria’s state railway, said initial investigations show that a supervisor neglected to trip a signal after manually activating a rail switch. The switch usually works automatically and sets off the signal but was stuck due to snow and ice.