With files from Rob Lurie and Cosmo Santamaria

More than 20 people fled their homes in a panic early Wednesday as fire ripped through an apartment building.

The flames erupted from the rooftop patio of a three-storey apartment building on Rouville St. near Prefontaine St. around 3 a.m.

One man said he was awakened by people screaming "Fire!"

"I was wondering if the fire was in the building itself, but it was just... on the roof, so we just took everything and we just went out," he said.

The man said people were panicking, but working together.

"I saw people trying to help people to get out of the houses and I was a little bit shocked, a little traumatized, but at least we are safe that's the most important," he said.

More than 100 firefighters responded to the three-alarm fire, and one firefighter was slightly injured.

Throughout the morning firefighters remained on the scene, inspecting walls and other areas to ensure they had extinguished the fire.

Fire Chief Louise Desrosiers said residents of most of the 16 units in the building should be able to return home later in the day, except for those who lived on the top floor.

"The units on the third floor, that are located on the third floor, some of them won't be able to go back inside their place," said Fire Chief Louise Desrosiers.

The Red Cross is providing temporary shelter to the six residents, including those living in the two units that suffered the most damage.

The cause of the fire is not known.