Six people died in an incident when a truck rolled into a neighbourhood party in the town of Nieuw Beijerland in the south of the Netherlands on Saturday evening, Dutch police said on Sunday.
Seven other people were in hospital on Sunday morning with injuries due to the incident, with one of them in critical condition, police said.
The incident happened around 6 pm (1600 GMT) around 30 km (19 miles) south of Rotterdam, when a heavy truck rolled off a dyke into a field where neighbours were holding a party.
It was still unclear what had caused the accident, police said.
The driver of the truck, a 46-year old man from Spain, was detained as he was suspected of having caused a fatal car accident.
Police said there were no signs of alcohol abuse by the driver, but provided no further details on the possible cause of the incident.
A spokesman for the man's employer, Spanish transport company El Mosca, told Spanish newspaper La Verdad that the driver went off the road running along the dyke as he tried to prevent a collision with a van.
Police did not confirm this report, but did say they had questioned a driver of a white van as a witness.