Petaluma police are investigating a potential arson case after a resident's doormat was apparently set on fire early Saturday morning.

A resident called to report arson in the 1000 block of Aspen Way at a little before 6 a.m., police said in a news release.

The homeowners told police they had woken to the smell of smoke. When they opened their front door, they found the mat outside the door on fire along with what appeared to be some kind of flammable liquid.

The flames damaged the mat and the door's trim but were extinguished before the fire could cause more damage, police said.

Police are still investigating the case and ask anyone with information to call 778-4373 and refer to report number 14-0468.