Four unoccupied Philadelphia Police Department vehicles were set on fire overnight, burning them but not injuring any officers or passersby, authorities said.

Shortly after 1:30 a.m. Monday, authorities said, someone set fire to the front passenger side of a police cruiser outside the Sixth District station, near 11th and Vine Streets. About 15 minutes later, they said, the left rear tire was burned on another empty cruiser near Seventh and Chestnut Streets.

Then, about 2:30, two more cars were set on fire farther west, authorities said. One vehicle was parked outside the University City District’s headquarters on the 3900 block of Chestnut Street, they said, and the other was a mile away on the 400 block of North 39th Street in Powelton.

On North 39th, authorities said, they determined the cruiser was set on fire with a Molotov cocktail placed on the hood of the driver’s side.

In the later incidents, police said they used University of Pennsylvania Police security cameras to identify a suspect. In surveillance footage, a man wearing a flannel shirt and a backpack was seen leaving the area on a white Cannondale bike, authorities said.

It was unclear whether police considered him a suspect in all four incidents or just the two in West Philadelphia.

Investigations into the arsons are ongoing, police said, and no additional information was available.

It was unclear whether the property damage was linked to the recent protests across the city or the calls for police reform nationwide in light of the death of George Floyd.