Some 1,500 people displaced from their Parliament Street apartments by a ferocious blaze on Tuesday afternoon will likely not be able to return for at least several days, as Toronto fire officials investigate its origin and assess damage to the highrise apartment building.

"We are working on an all-hands-on-deck model right now," Toronto fire chief Matthew Pegg told reporters on Wednesday afternoon.

"There is a lot of work to be done in any fire investigation and certainly in one of this size."

Twenty-six trucks and 100 firefighters battled the blaze at its peak. After power to the building was knocked out, firefighters were forced to carry equipment as many as 20-storeys.

Toronto fire investigators, along with Ontario's Office of the Fire Marshal, have commenced a probe into the cause of the blaze.

"Our goal is to complete investigation and inspection as quickly as possible such that we can return the building back to the owner and begin the restoration process," said Pegg.

The fire chief said most of those forced from their homes were able to return briefly overnight to gather essential belongings, such as medication. Given the lengthy process of assessing damage and then fixing it, Pegg said, "we're looking at at least a few days" until some tenants may be able to return to their homes.

Mayor John Tory said the lack of electricity in the building means the building is unsafe to live in because fire-safety systems and elevators are not functioning.

Tory said he talked with the property manager of the building, who assured him they have electricians and restoration workers on standby, ready to begin repair work as soon as the investigation is complete.

"But we are talking potentially here about a couple days before even that work is possible," Tory said.

150 units of accommodation still needed

Tory said around two-thirds of residents were able to find accommodation with friends and family Tuesday night. The rest were provided with hotel and motel rooms or given emergency accommodations at two community centres in the area: Wellesley Community Centre and Regent Park Community Centre.

Still, Tory said the city is hoping to find more suitable accommodations for the people who had to stay in community centres. He said they need 150 units of accommodation for the remaining families.

Toronto Fire Chief Matthew Pegg addressing reporters Wednesday afternoon outside the St. Jamestown apartment building where a six-alarm blaze caused the evacuation of 1,500 residents. (Christopher Langenzarde/CBC)

"I am reiterating my plea today to people in the hotel industry and to those who might have Airbnb-type units ... we are asking them to be in touch with us," said Tory on Wednesday afternoon.

"We would like to be able to say by the end of day tomorrow there are no people left staying in community centres because at least they're in a hotel, which gives them the opportunity to have better accommodations and their own shower," Tory said.

On Wednesday evening, a spokesperson for Airbnb told CBC News the company had activated its Open Homes program, which connects people who have been displaced by major disasters with temporary accommodations free of charge.

People in the hotel or motel industry and residents who have rooms registered with shared accommodation services are being asked to call 1-855-797-8875.