A gunman disguised as a police officer went on a rampage in the state parliament building in Zug, a lakeside resort near Zurich. At least 14 people were reported killed and more than 10 wounded, several seriously.
Reports say the gunman stormed into Zug's state parliament armed with a rifle and an explosive device.
Eyewitnesses say he shot wildly around him for several minutes and threw the device. Witnesses say the force of the explosion was strong enough to rip off several doors and shatter windows.
The Zug police chief, Urs Hurlimann, says the gunman was among the dead. He did not give details on how the man died. But, other police in Zug report the man killed himself.
The victims also include three members of the local government.
About 30 ambulances and two helicopters were rushed to the scene. The injured were taken to the local hospital. Police Chief Hurlimann says eight lawmakers were seriously injured, including the president of the cantonal government. Police describe the scene as chaotic and say the assembly room was covered with blood.
Police Chief Hurlimann says the attack does not seem to be connected with the terrorist attacks in the United States. He says the man was acting on his own and was upset about a local government decision.
Swiss radio reports the man, who was Swiss, left a letter in which he spoke of a "day of rage against the Zug Mafia."
The president of the Swiss national parliament in the capital, Bern, interrupted the regular session to announce the death toll. Security was immediately tightened around the federal parliament building.
The attack has sent shock waves through this normally tranquil country. Violent crime is low and politicians rarely have police protection. The president of the Swiss parliament says security might now have to be reviewed.