AUBURN — Firefighters were able to revive a cat that was trapped in a burning apartment house on High Street early Monday.

No tenants in the six-unit building at 68 High St. were injured, despite full occupancy at the time the blaze was discovered, Deputy Fire Chief Matthew Fifield said.

Firefighters arrived shortly after 5:30 a.m. to find a second floor window ablaze at the front of the building. It took firefighters about 15 minutes to extinguish the blaze, he said.

No cause was determined as of Monday evening.

Investigators from the Maine State Fire Marshal’s Office and a local fire inspector were at the scene seeking the cause of the fire, which appeared to have started on the second floor, Fifield said.

Firefighters were told some of the tenants’ whereabouts were unknown, so they entered the building only to discover it unoccupied, except for a cat on the third floor.

They brought the pet outside where they administered oxygen until the animal became responsive.

The cat was turned over to its owner who planned to take it to an emergency veterinary clinic in Lewiston, Fifield said.

No tenants reported any injuries.

One firefighter went to a hospital for evaluation of a knee injury, Fifield said.

The building’s landlord was on scene to assist with relocating tenants, along with the American Red Cross, which also helped with other needs.

Despite heavy smoke and fire damage to the second floor and significant smoke damage to the third floor, the building should be repairable, Fifield said.

Lewiston Fire Department assisted local firefighters at the scene, while fire crews from Mechanic Falls, Minot and Poland stood by at local stations.