A massive blaze that destroyed a condo building in Saskatoon's Sutherland neighbourhood on Friday was caused by the improper disposal of smoking material in a plastic container, fire investigators say.

During a news conference on Sunday, Saskatoon fire Chief Morgan Hackl said investigators found the blaze broke out on the ground floor exterior of the building's northwest corner because of improper disposal of smoking material close to the building. The container didn't have sand or water at the bottom to snuff out the materials.

It ignited, starting a fire that would cause about $5 million in damage.

Firefighters were on scene 2½ minutes after they received the fire call at 11:30 p.m.

When the first crews arrived, the building's entire north and west walls were fully engulfed in fire and the flames were moving across the roof of the three-storey building at the corner of 108th Street and Bryans Avenue.

Firefighters spent seven hours fighting to take control of the growing blaze — much longer than the usual hour it takes to get a fire under control, Hackl said—and another 7½ to fully extinguish the blaze.

By the end of the more than 14 hours at the site, more than 80 staff had been involved in tackling the fire.

Firefighters rescued five people from their condo units, officials said, some of whom had mobility issues and couldn't escape their suites.

Of the 24 suites in the building, 23 were occupied at the time of the fire. One person was assessed for injuries on scene but no one was hospitalized. 

While there were no injuries to occupants or firefighters, Hackl said firefighters had to enter a "dangerous situation" to rescue the occupants.

In his 35 years as a firefighter, Hackl said, he's seen other similar fires and those that burned with this intensity also had highly flammable exteriors.

On Sunday afternoon, people continued to stop to take photos of the wrecked building close enough to smell the soggy ash.

Just inside the fence of the caged building, there were clothes still on hangers strewn about the rubble. The northwest side of the building looked as if it had been cleaved off, with insulation jutting out and torn wires hanging like vines in front of what appeared to be a kitchen. Hackl speculated that the fire could have been less severe had it not been for the modern building materials used in its construction.

"A structure, which has vinyl siding, lots of different glulam [a structural material manufactured through the union of individual wood segments] and oriented strand board material that has glue content in it: When fire catches onto that product it moves very quickly; it burns very hot," Hackl told reporters.

The fire climbed the vinyl siding and "quickly moved in to the open truss space in the roof," he said.

Hackl said associations and unions continue to push for better construction materials.

"There's been very good focus on the interior of buildings and early activation, and we continue to advocate for the exterior of buildings," he said.

Several buildings on 108th Street W. were also evacuated, though none were damaged by the fire, and the road was completely closed to traffic.

Four vehicles were damaged by the fire.

The fire wasn't fully under control until about 5 a.m. Saturday. Part of the structure was taken down by an excavation company to ensure all hot spots had been extinguished and to prevent further collapse.

Hackl emphasized one aspect of the residential fire response: No one pulled the fire alarm, even though it was working. He said it's important, especially in multi-residential complexes, that people pull the alarm and alert others in the building.

"A lot of the early intervention by the public was actually people on the exterior of the building trying to warn people to get out, and also someone within the building moving throughout the hallways and alerting people by yelling," he said.

The building didn't have sprinklers in suites or common spaces.

Maj. Mike Hoeft, area commander for the Salvation Army Saskatchewan, told CBC News the organization arranged hotel rooms for 12 families displaced by the fire on Saturday.

Hackl said as far as he was aware, everyone had been rehoused either with family, friends or through an organization. He was uncertain how many people needed to be sheltered.

The site has been turned over to the condominium boards' property management company and required to be secured.

Dayne Patterson is a reporter for CBC News in Saskatchewan and is based in Saskatoon. He has a master's degree in journalism with an interest in data reporting and Indigenous affairs. Reach him at dayne.patterson@cbc.ca.

With files from CBC's Jacob Zehr

Audience Relations, CBC P.O. Box 500 Station A Toronto, ON Canada, M5W 1E6

Toll-free (Canada only): 1-866-306-4636

TTY/Teletype writer: 1-866-220-6045

It is a priority for CBC to create a website that is accessible to all Canadians including people with visual, hearing, motor and cognitive challenges.

Closed Captioning and Described Video is available for many CBC shows offered on CBC Gem.