Fire crews continue to battle a four-alarm fire at a high-rise complex on Thorncliffe Park Drive near Overlea Boulevard that’s displaced residents due to concerns over high carbon monoxide levels.

Firefighters were dispatched to the scene at 11 Thorncliffe Park Drive at around 1:36 p.m. Thursday afternoon.

Early indications point towards an electrical fire that started on the P1 (parking) level and spread to the interior wall.

In an update, Toronto Fire Commander Robert Hewson said the fire began spreading through the wall’s insulation, with smoke migrating to a neighbouring building at 21 Thorncliffe Park Drive.

“There is insulation burning in between the walls,” he said. “It’s a very stubborn and slow fire.”

Toronto Hydro shut down power and gas to the two buildings and TTC buses were summoned to provide temporary shelter for affected residents. Power has since been restored to most of the units.

Hewson said high carbon monoxide levels were detected in both buildings, prompting evacuations on several floors.

Seventy units were evacuated as a precaution, he said.

“It is producing some CO (carbon monoxide) levels that we are cautious with for tenants … so we have brought (those) tenants down and they are sheltering on TTC buses. We are working on extinguishing the fire and CO-levels are going down currently.”

Paramedics tell CityNews they’ve been on scene since shortly after 2 p.m. but so far no injuries have been reported.

Hewson said it’s too early to say if the affected residents will be allowed back into their units tonight.