A house caught fire in Saint John at around 3:30 a.m. Sunday.

The Canadian Red Cross credited barking dogs with alerting two women after a house caught fire in Saint John at around 3:30 a.m. Sunday. The women, their three dogs and five cats were uninjured in the blaze.

Canadian Red Cross disaster volunteers arranged emergency lodging, food and other help for the two women.

The older duplex in the city's lower west side suffered extensive damage.

The cause of the fire is under investigation.

Platoon Chief Eric Garland said when fire crews arrived the two-storey wooden building, which had three storeys in the back including an above ground basement, was engulfed in heavy flame with smoke coming from the rear wall.

"The fire had spread up the rear wall and started to penetrate the structure," Garland said.

In addition to the two women, Garland said a family of four lived in the structure but were out.

Police and the fire officials said they are investigating because the fire seems to have started on the outside of the building.

"It appeared to be a fire that was predominantly on the outside wall," said Garland. "Because of that we brought in a fire investigator which we generally do whenever we don't have a definite explanation right away."