At least four people were killed and six injured in Wednesday's shooting incident at a timber processing plant in the village of Menznau outside Lucerne, police have confirmed.
The gunman, a 42-year-old Swiss who had been with the Kronospan company for more than 15 years, is among the dead. He used a pistol and reportedly shot himself.
The suspect fired a Sphinx AT 380, which is not an army-issue gun, Lucerne police said on Thursday. It is still unclear how he came into the possession of the pistol and whether he legally owned the weapon.
Police announced they detained its alleged previous owner for questioning.
The suspect had a criminal record and was sentenced for robbery in 1998, according to the justice authorities. He was from an immigrant background and the father of three children.
The shooting occurred shortly after 9am on Wednesday, according to the police. The gunman had apparently picked out the victims, all of whom were Swiss.
A spokesman for the investigating authorities said the shooting took place over two to three minutes, with the dead and injured found on the factory floor, in a corridor and the site canteen.
The Kronospan factory employs about 450 people. Menznau is located about 25 kilometres from Lucerne in central Switzerland.
Kronospan chief executive Mauro Capozzo said the suspected assailant, who was still with the company at the time of the shooting, was "a quiet man, no other incidents involving him are known". He added that the company hadn't laid anyone off recently.
Justice Minister Simonetta Sommaruga said the incident showed how much suffering can be caused with weapons, but also that the legislation has to be continuously improved. There are still hundreds of thousands of unregistered weapons in Switzerland, she added.
Gun ownership is widespread in Switzerland, the result of liberal regulation – a 2011 initiative to tighten controls failed – and a long-standing tradition for men to keep their military rifles at home after completing compulsory military service.
An estimated 2.3 million firearms are owned by the country’s eight million people.
There have been several high-profile incidents over the years, including the killing of 14 people at a parliamentary session in canton Zug, in 2001.
Last month, a 33-year-old man killed three women and wounded two men in a southern Swiss village.
If reports of gun violence are relatively few and far between in the Swiss media, it is because most cases are suicides, a subject the press traditionally avoids.
Between 1996 and 2005, 3,410 suicides (24-28 per cent of all those in Switzerland) were committed using firearms. That percentage trails only the United States, where 57 per cent of suicides involve a gun. Few European countries come anywhere near Switzerland.
swissinfo.ch and agencies