Police in Aargau canton were called to the town of Würenlingen overnight after local residents reported hearing gun shots.

Officers dispatched to the scene reportedly found "several" dead people lying outside and in a house.

Investigators said in a statement that all those killed were adults.

A police spokeswoman told local radio the suspected killer was among the dead.

Police are expected to hold a press conference later on Sunday.

Würenlingen is a community of around 4,500 people northwest of Zurich.

nm/jr (Reuters, AP)