Firefighters used machinery to knock down walls and get at the last remnants of the fire. (Steve Fischer/CBC)

A vicious four-alarm fire has completely destroyed an 18-unit apartment building in Ottawa's Glebe neighbourhood, leaving the residents homeless.

"The building is pretty well totalled," said Pierre Savaray, spokesman for the Ottawa Fire Service late Monday as firefighters prepared machinery to knock down walls and get at the last of the hot spots.

No one was hurt in the blaze that broke out before 2 p.m. Monday on Glebe Avenue near Bank Street, but damage is estimated in the millions of dollars, fire officials said.

Dozens of firefighters worked late into the night to extinguish the remnants of the blaze and ensure it didn't spread to nearby buildings. Some of those neighbouring buildings did suffer water damage and the power was temporarily cut off to one of them, but they were untouched by the fire itself, Savary said. A section of Bank Street was shut down for six hours.

Cause may never be known

The fire caused millions of dollars in damage. (CBC)

The fire-ravaged building was left so unstable that it could be days before Ontario's fire marshal can get inside to investigate and the damage is so bad that he may not be able to determine what caused it, fire officials said.

Adam Gallaro, who lived in the building for two years, said its destruction raises awareness about the potential hazards of such older buildings.

"I think that every single building in the Glebe should be inspected, should be checked," he said. "Even though they have beautiful charm and they're lovely places, this kind of stuff happens when you have older buildings."