An explosion has hit a three-storey block of flats in The Hague, police say.
Firefighters rushed to the scene to put out a fire that caused the collapse of several homes in the city's Tarwekamp area at around 06:15 (05:15 GMT).
Rescuers are looking for up to 20 people thought to have been there at the time of the blast. Four have been pulled out of the rubble so far.
The cause of the explosion is not yet clear, but Dutch police said a car drove away "at very high speed" shortly after, and have appealed for witnesses.
Dutch media reported five flats were destroyed in the explosion.
Rescue teams with sniffer dogs have been deployed to sift through the debris, but parts of the site remain too dangerous to access.
Fourteen-year-old Adam Muller told the AFP news agency the explosion "felt like an earthquake".
"I was asleep and suddenly there was this huge bang," he said.
"I looked out of the window and just saw flames. It's a massive shock," he added.
National police commissioner in the Netherlands Janny Knol said there was "disbelief and uncertainty" in the community.
Dutch King Willem-Alexander and Queen Máxima said in a statement: "We sympathise with all those who have been personally affected or who fear for the fate of their loved ones."
Police are expected to provide an update at 15:00 local time (14:00 GMT).