Several people were killed in a shooting late on Saturday in a town in the Swiss canton of Aargau, local police said on Sunday.
Officers responding to reports of shots found several bodies in and around a residential building in Wuerenlingen, a community of some 4,500 people north-west of Zurich, police said in a statement.
The killer was assumed to be among the dead, a police spokesman told local radio.
All those killed were adults and an investigation was under way, the statement said. It gave no further details and the spokesman declined to say how many people had been killed.
A neighbour, who was also not identified, told Swiss newspaper Blick she heard four shots in succession fired very quickly, then two further shots after a pause. She had heard no screams, the tabloid reported.
Police said they would hold a news conference at 11:30 GMT on Sunday.
The residential area in which the shooting took place is made up of family houses, newspaper NZZ reported.