Police launched a manhunt after a shooter killed two people and wounded a third in the Swiss Alpine town of Sion early on Monday.
A 36-year-old man fired several shots in two parts of the town, police said.
Initial research suggested he knew his victims, but investigators were still working on establishing his motive, police added.
Search efforts to find the shooter
Officers cordoned off the scene and set up a checkpoint, stopping and searching cars on the main road out of the surrounding southwestern canton of Valais.
The man was "dangerous" and the public should not approach or confront him, police said.
Switzerland has a high rate of gun ownership. The Swiss-based Small Arms Survey research group estimates that in a country of around 9 million people, civilians own about 2.3 million firearms.