A fire investigator tosses debris July 19 from a second-story window of an apartment building at 68 High St. in Auburn. A team from state and local agencies investigated the cause. Russ Dillingham/Sun Journal file

AUBURN — A fire that swept through an apartment building last week displacing more than a dozen tenants remains under investigation.

In all, 14 tenants who lived at the six-unit building were unable to return to their homes after the 5:30 a.m. fire heavily damaged the second floor and caused extensive smoke damage to the third floor, fire officials said.

A firefighter suffered a knee injury at the scene, officials said.

All of the tenants were able to escape the fire without injury, but an unresponsive cat found on the third floor by firefighters had to be revived with oxygen before it was turned over to its owner for treatment at an emergency veterinary clinic.

The fire started on the second floor, according to fire officials, who said the building appeared to be repairable.