The explosion in the town of Bovenkarspel, north of the Netherlands’ captial, shattered windows but caused no injuries.
Police spokesman Menno Hartenberg told the Reuters news agency that remains of the explosion were found in front of the building and it “must have been placed there”.
He added: “We don’t know yet exactly what exploded, the explosives experts must first investigate,.
“What we’re saying is that something like that doesn’t just happen by accident, it has to be laid.”
A security guard who was inside the testing centre at the time was not injured, according to national broadcaster NOS.
This story is being updated.