Residents of 2095 Prospect St. were displaced by the blaze, which started around 4 a.m. in the underground parking lot and caused an estimated $300,000 damage.

Two vehicles were destroyed and two apartment units sustained damage from the fire, which is being investigated by arson experts from Halton police.

At Post press time, residents from 56 units had been allowed home.

"Firefighters escorted people back systematically, floor by floor," said chief fire prevention officer Dave Cioruch. "We had control of the building and were assisting people to make sure they were OK and we were testing their fire alarms."

The fire official said the building started to be reoccupied after electrical cabling was inspected, elevator operation was confirmed and major structural problems were ruled out. He said some shoring up was required to prevent fire-damaged concrete from falling.

Meanwhile, residents in 18 apartments took temporary accommodation provided that night by the Red Cross, friends and family.

The Red Cross provided food, shelter, clothing and personal items to 15 of the overnight evacuees through its Personal Disaster Assistance (PDA) program.

"Losing one's home is difficult," said Jack Lodge, chair of disaster management for the Halton area. "We are here to help by providing basic necessities as well as comfort to those affected, so they can concentrate on deciding what to do next."

Lodge said the Salvation Army opened its doors and started feeding people almost immediately after the evacuation.

"There was great co-operation between the agencies," he said.

Cioruch said late Friday that nine apartments were still not able to be occupied. They include three that are having electrical problems, four more with extensive damage and two basement apartments that won't be occupied until fire alarm and wiring repairs are completed.

Wiring that burned initially in four units (101, 201, 301 and 401) also affected other apartments on lower floors, he said.

"There's no risk or damage to the electrical power supply for the fifth through eighth floors," said Cioruch. "The four apartments affected are directly atop where the cars are parked. Their wiring melted and burned."

He said units 101 and 201 sustained fire damage, while 301 and 401 need new electrical cabling to their circuit breakers.

"Those four apartments will not be back and occupied quickly," said Cioruch.

He noted all affected apartments have breaker panels, which is making it easier to restore power to other units.

Cioruch said the two basement apartments escaped fire damage, but will be out of commission while work in that area -- including repairing wiring and fire alarms -- continues. He said the area will be watched around the clock until fire alarms there are repaired.

Cioruch said there was a lot of smoke in the building and he praised tenants for responding quickly, instead of assuming it was a false alarm.

"Residents should be commended for the way they did evacuate, so (firefighters) could be delegated to the task of fighting the fire, rather than rescuing people," said Cioruch. "That helped dramatically."

Police said there have been some thefts from vehicles in the area, with some property recovered. Investigators are still looking into whether the fire was intentionally set.

Anyone with information about the fire is asked to call Crime Stoppers of Halton at 1-800-222-TIPS (8477) or visit www.haltoncrimestoppers.com.