At least three people were killed in an apparent family shooting at a home in the southern Dutch city of Dordrecht on Monday evening, police and news reports said.
"The shooter is believed to have been a policeman who also shot himself," the tabloid newspaper De Telegraaf said, adding a fourth family member was seriously wounded and taken to hospital.
Rotterdam police tweeted that "three people have been killed and another was seriously wounded" but did not give any further details.
"We are at the scene with numerous people to investigate the cause of the incident," police said, adding that more details would be given later.
Dordrecht's mayor Wouter Kolff tweeted that he was "very touched and sympathise with everyone involved".
Dordrecht lies around 25km southwest of the port city of Rotterdam and is one of the oldest cities in the Dutch province of South Holland