ST. PAUL, Minn. - A historic structure in St. Paul is uninhabitable after a fire tore through it Tuesday.

Crews were dispatched to the one-time mansion, most recently serving as multi-unit housing, located at 251 Dayton Avenue. By the time engines arrived heavy fire was already showing. Firefighters attempted an inside attack but were forced to retreat due to advancing flames and concerns over the soundness of the structure.

Additional alarms were sounded and more than 50 firefighters began an exterior attack. Eventually, the second floor collapsed onto the first. Fortunately, all residents and firefighters got out safely before the collapse. No injuries have been reported, although two cats died in the fire.

The daughter of the home's owner tells KARE 11 that part of the house was recently renovated. Alida Purmalietis says her family has owned the home since the 1970s, and that 10 or 11 people live there. She says some who were home at the time the fire broke out were barely able to escape.

Another person on the scene, who has studied the history of the Cathedral Hill neighborhood says the structure is known as the Alpha Lascher House and maintains it is the fifth oldest house on the hill. Documents show it was built in 1864.

Kim Aughenbaugh's son, Dana, lived in the house with his girlfriend, the owners' granddaughter.

"They've been restoring this house ever since they got it," Kim Aughenbaugh said. "It's hard to start over."

She said the the owners, Maris and Norma Permalietis, are in their 70s and their source of income was the rent from the tenants living there. That's why her son, Dana, started a GoFundMe for them.

"They're going to need a lot of help," she said. "They have nothing left."

Family members believe the fire may have started in a storage room on the second floor. Investigators are looking into that area, but the cause is still under investigation.