Cannabis cafes in Amsterdam which have been hit in a recent spate of shootings will no longer be automatically closed down, the city’s mayor Eberhard van der Laan said on Wednesday.

However, the cafe owners will have to agree to cooperate fully with the police and take measures to beef up their security, such as installing surveillance cameras, the mayor said.

Several cannabis cafes have come under fire during the night since the summer, some of them more than once. The cafes were empty at the time, nobody was injured and nothing was stolen.

Police have not ruled out the possibility that rival coffeeshop owners are behind the shootings.

Under the mayor’s security measures, any cafe hit by gunfire is automatically shut down. People in the trade say this may unwittingly have encouraged unscrupulous owners to resort to bullets to put their competitors out of business.

On Tuesday police arrested their first suspect in the investigation into the shootings.