The grounds of Kasteel Park Den Brandt in Antwerp were closed on Wednesday morning by the police after a grenade was found in the Grand Café restaurant.
Early on Tuesday night, there was also a suspected arson in restaurant Murni, in one of the coach houses of the Kasteel.
"Last night the police were sent to the castle because of several burglar alarms", said Wouter Bruyns of the Antwerp police in a statement. "When checking for possible suspicious circumstances, our teams saw that there was a build-up of smoke in the restaurant."
The fire brigade immediately arrived at the scene, and the damage was limited, given the circumstances. Police assume that arson was intentional. "But in view of the ongoing investigation, we cannot give any further details", added Bruyns.
Damage was also caused to the front of the building, on the Grand Café.
The Office for the Disposal and Destruction of Explosive Equipment (DOVO) was sent to the site to rule out danger after finding a possible explosive. They will handle the explosive, and ensure the situation is safe.
The Brussels Times