Swiss television is quoting police as saying that two trains collided at Granges-près-Marnand in the western canton of Vaud on the evening of July 29, injuring about 44 people, four seriously.
Rescuers, firefighters, and police have been working at the scene of the accident.
The crash happened on a regional line about 50 kilometers southwest of the capital, Berne.
A local newspaper quoted a passenger as saying that one of the trains was approaching the station while the other one was pulling out.
No further details were immediately available.
Earlier this month, 79 people were killed in a high-speed derailment in Spain.
Based on reporting by Reuters, AP, and ITAR-TASS