Police said in a statement that the 35-year-old officer was suspected of being the shooter.
It was not immediately clear if he was related to the children, who were aged 8 and 12, or to the 28-year-old injured woman, but police spokesman Wim Hoonhout told The Associated Press in a telephone interview that “it seems like a family incident.”
Police said further investigation was needed to definitively establish the motive.
Emergency response teams were at the scene, a home in Dordrecht, near the port of Rotterdam. Forensics teams were also present.
Photos from the scene showed a large police presence in a residential neighborhood and at least one ambulance parked in the street as people stood in the street looking on.
Dordrecht Mayor Wouter Kolff said on Twitter he was planning to visit the site of the “very serious shooting incident.”
Eerder vanavond heeft zich een zeer heftig schietincident voorgedaan in Dordrecht. Ik ben zeer geraakt en leef enorm mee met alle betrokkenen. Later vanavond zal ik naar de Heimerstein gaan. https://t.co/g6L5In4FXN
— Wouter Kolff (@WouterKolff) September 9, 2019
Reuters contributed to this article.