Three men were "badly injured" after gunman opened fire on people praying at an Islamic Centre in Zurich police said.
The victims, aged 30, 35 and 56 were hit at around 5:30pm local time.
An official said officers were swarming to the scene in pursuit of the gunman who remains at large. He was not authorized to speak publicly about the matter.
Attacks by armed gunmen are rare in Switzerland.
