PARIS (AP) — French firefighters tackling a fire set deliberately in a school in the northern city of Lille were pelted with projectiles by people in nearby buildings, authorities said.

The incidents Thursday night come amid rising tensions between the northern region’s citizens and police, as lockdown restrictions and perceptions of government elitism have led to frustration in poorer areas.

Lille Mayor Martine Aubry firmly condemned the act of “voluntary arson.”

No one was injured in the fire, which was extinguished very quickly.