A gunman has killed three relatives and a neighbour before turning the gun on himself in the Swiss town of Wuerenlingen, near Zurich, police say.
The attacker, who was separated from his wife and three children, shot dead his parents-in-law and brother-in-law on Saturday night, they added.
The 36-year-old then went into a second house and killed a male neighbour.
Wuerenlingen, a German-speaking town of some 4,000 people, is located about 30km (20 miles) north-west of Zurich.
Police found the bodies lying inside and outside a residential building overnight.
They were quick to rule out any links to terrorism, instead labelling the attack a "tragic relational drama".
All of the victims and the gunman were Swiss nationals. The gunman, who has not yet been identified, had a record of violent behaviour and lived apart from his family, police spokesman Michael Leutpold told reporters at a news conference on Sunday.
He did not have a gun license, Mr Leutpold confirmed.
The attacker's wife and children had reportedly left the family home to be housed in a shelter just before the attack unfolded.
"The mother and her children are safe," another police official, Markus Gisin, said.
Police say the investigation into the shooting may be difficult as there are multiple crime scenes.