AUBURN — A historic Court Street apartment house burned Thursday afternoon, leaving tenants scooping up pets and scurrying to safety as fire crews battled the stubborn blaze.

When fire crews first arrived at about 1 p.m., they found heavy fire ripping through the porches at the back of the building, on the Pleasant Street side. Flames quickly burned into the upper floors of the building as firefighters entered to determined that all occupants were out.

When the fire was first called in, there were reports that at least one person was unaccounted for, although it was later established that two tenants had stayed behind to collect pets from the burning building. Several animals were rescued, including one cat that firefighters brought down from the roof.

At least one witness reported hearing a boom just before flames and smoke appeared. Another heard what sounded like two pops.

Firefighters battle a fire Thursday afternoon at an apartment building on Court Street in Auburn. Andree Kehn/Sun Journal

An investigation into the cause of the fire was continuing into Thursday night. Fire officials said there were no early indications that the blaze was suspicious.

As firefighters fought the fire from above, below and within, flames appeared to surge again at about 1:40 p.m., burning into the attic and through the roof as firefighters worked from ladders. Around that time, firefighters inside the brick building were ordered outside.

In addition to Auburn, fire crews from Lewiston, New Gloucester and Poland battled the fire, contending with 85-degree temperatures and high humidity. Fire crews from Oxford and Durham filled in at the Auburn fire station. A water station was set up next to a United ambulance in a parking lot off High Street.

Auburn Deputy Fire Chief Matthew Fifield said he called in help from extra departments due to the heat, which can quickly sap a firefighters stamina. No injuries or heat related maladies were reported as fire crews battled the fire.

“Usually between Lewiston and Auburn we could handle this,” Fifield said, “but the heat was difficult on our staff.”

Police blocked a section of Court Street between Turner Street and Minot Avenue, causing minor traffic snarls on surrounding streets as motorists sought other ways around the fire scene. The street was reopened shortly before 4 p.m.

By 2:45 p.m., the flames were out but fire crews remained at the scene, snuffing out hot spots and mopping up.

The brick home was built in 1900 and was among the first to go up on Court Street. It sits up on a hill with two buildings on either side. Fire officials were still investigating the cause of the blaze Thursday night and still assessing damage to the building.

Two porches on the back of the apartment house were gutted and there appeared to be extensive damage on the upper floors. The first floor sustained smoke and water damage, Fifield said,