The residents were robbed at their home between 08:00 and 08:30. The man had a package with him, police said. It is not clear whether the man made any loot.
An ambulance arrived to provide medical support. No one had to be taken to hospital.
A citizen network report has been sent out to track down the suspect. The man is about 25 years old and 1.80 meters tall. He has a light skin color, speaks Dutch without an accent and he wore an orange jacket and a cap.