There is no evidence that a drugs lab was located in the apartment complex in The Hague that was partially destroyed by an explosion early on Saturday morning, police said on Monday afternoon.

The blast was likely to be the result of criminal behaviour, but experts are looking at other scenarios, and as yet it is still unclear what caused the explosion, which damaged 19 homes.

Six people were killed in the blast, of whom three were members of the same family. An eight-year-old boy, their son and brother, survived the explosion and fire. The remaining three victims are all men, aged 31, 44 and 63.

Four people are also in hospital, two of whom are very seriously ill.

The police are still appealing for information about a car that drove off at high speed shortly after the blast, and are examining another burnt-out vehicle found at the scene. They also want to speak to people who smelled of smoke or had visible burns.

Meanwhile, the first residents of the block have been allowed home to pick up some of their belongings.

At least 10 people have been killed and five injured in explosions and chemical leaks at drugs labs in the Netherlands and just over the border in Belgium this year.

In February three people were killed in an explosion at a drugs lab in Rotterdam and two weeks later, one person was injured in a “massive” blast in Herveld in Gelderland.