OTTAWA -- Investigators are searching for the cause of a fire that destroyed a commercial building in the heart of Vanier.

According to Ottawa Fire, an employee at 81 Montreal Rd. called to report a haze inside the building around 6:45 p.m. Thursday. When crews arrived on scene, the smoke continued to worsen. A second alarm was declared by firefighters when they found flames burning in multiple parts of the building, including the floors and walls.

A short time later, fire crews had to evacuate after the building started to show signs of collapse. A third alarm was called at that point. Firefighters continued with a defensive attack, trying to save the buildings surrounding the fire.

The blaze was in a two-storey building that houses a pawn shop, an appliance store and a church.

UPDATE: Fire crews continue to battle massive fire on Montreal Rd. in Vanier. Crews on scene say this is now a defensive attack. No injuries reported #ottnews (: Lise Ausman) pic.twitter.com/VWkgd7RySX — CTV Ottawa (@ctvottawa) February 28, 2020

Damage is estimated at $600,000.

Investigators are trying to determine the cause of the blaze. At 9:30 a.m. Friday, Ottawa Fire spokesperson Jen McNeely told CTV News Ottawa that the "cause is undetermined because of severe damage."

Meantime, Ottawa By-Law says a vehicle parked in front of the building on Montreal Road was ticketed and towed to a nearby location.

In a tweet, By-Law Services says the vehicle was "not only in violation of the winter parking ban, but was also hindering their efforts in battling a blaze on Montreal Road."

Last night our officers assisted our colleagues from @OttFire by towing a vehicle that was not only in violation of the winter parking ban, but was also hindering their efforts in battling a blaze on Montreal Road.



Vehicle was ticketed and towed to a nearby location. #OttCity pic.twitter.com/e9aRd7LVLX — Ottawa By-law (@OttawaBylaw) February 28, 2020

Ottawa Fire on scene of a 2-Alarm fire at 81 Montreal Road. Fire is in a 2-storey commercial unit. #ottnews #ottcity #ottfire pic.twitter.com/7iYF5OVq42 — Scott Stilborn (@OFSFirePhoto) February 28, 2020