Investigators say it could be weeks before the cause of the massive fire at Rutherford Landing in southwest Edmonton early Sunday is known.

The fire happened at 119th Street and 21st Avenue and covered almost two city blocks. It brought down three buildings of a condo complex under construction, causing at least $20 million in damages.

One building was almost finished and owners were set to move in this December. The second building had its roof on and construction was just underway on the third.

In total, about 265 units were destroyed.

Investigation ongoing

Investigators have been on scene since 2 a.m. Sunday, when the fire started.

They've already upgraded the value of the condominium complex from $17 to $18 million, and expect damage to the homes directly across from the fire to exceed $1 million.

"I know our investigators just had preliminary chats with some of the homeowners, people who were affected from across the street," said Michael Tucker, spokesperson for Fire Rescue Services.

"That number is going to increase by quite a bit, I would imagine, as we get a better sense of the damages."

Investigators are also still tallying damage to construction equipment, equipment trailers and vehicles.

The construction company, The Carlisle Group, said it will begin rebuilding the complex, which was 90 per cent sold, as soon as the investigation is complete.  

With all the buildings levelled to the ground, there's a lot of rubble for investigators to sift through, said Tucker.

He said there are many witnesses to question as well.

“Everything's on the table,” said investigator Cpt. Shayne Page, who confirmed fire officials are still documenting work site damage.

“We’ve just started doing the scene examination. We’re ruling things out and we’re digging through the rubble to see what we can find.”

As for whether the cost of damage will continue to increase, “only time will tell,” said Page.

With files from CBC's Lydia Neufeld