Photo: CTV News

A blaze that injured one man and extensively damaged a south Vancouver apartment building is now considered suspicious.

Vancouver police Sgt. Steve Addison says detectives believe the blaze that started early Tuesday morning was sparked outside the apartment in the Marpole neighbourhood, then spread to the three-storey building.

He says witnesses report hearing fireworks and seeing a group of people walking away at the time of the blaze.

Firefighters rescued numerous residents from balconies, while two others, including a 33-year-old unconscious man, had to be pulled to safety from a smoke-filled hallway.

Addison says that man is recovering from serious injuries.

Police are now appealing for witnesses, video or any other evidence that can help the investigation.

"We believe someone out there knows how this fire started. We're asking them to do the right thing and come forward," Addison says in a statement.

The fire destroyed or significantly damaged many of the suites in the 24-unit building, and endangered dozens of people, he says.