A firebombing was likely the cause of an apartment fire that sent three residents to hospital, including an eight-month-old boy.

Neighbours say a young family was trapped in their fourth-floor apartment at 1494 Lepage Ave. when the inferno ignited in the fourth-floor highway.

"She was up in that window screaming that she had her baby," recalled neighbour Matt Chernawsky.

Firefighters were able to rescue the family late Tuesday night. All three were treated in hospital for smoke inhalation; the father was listed in serious condition upon arrival. They have since been released.

Arson investigators remained on the scene for most of the day. Police say it appears the fire was started by a Molotov cocktail thrown down the hallway.

"We've seized some evidence at the scene and it appears to be a form of a Molotov cocktail," said Sgt. David Christie.

Police are unsure if a particular unit was the target of the blaze. However, investigators say these types of incidents aren't usually random attacks.

"It's possible that it was a random incident, but I would think it probably wasn't. It's just at the moment we haven't established what the motive would be," said Christie.

The family has lived in their fourth-floor unit on Lepage Avenue for six years. They told police they don't know who would have wanted to hurt them.

About 20 residents were evacuated from their apartments for several hours. Some will not be allowed back into their units for a few days.

With a report from CTV Ottawa's John Hua