A major fire at a Burlington townhouse complex left four firefighters with minor injuries and pushed the residents of 18 units out of their homes.

"I turned around to look up, and the whole upstairs end unit, and right above us, the roof was just a ball of fire,'" resident Jeremy Jones told CTV Toronto on Saturday.

"All I heard was this voice that said, 'get out, get out -- there's a fire'," Justin Jones said.

Maureen Rossouw was one of the residents warning her neighbours. "I'm banging loud and shouting, 'get out, get out, get out -- and bring your animals as well'," she said. "And one of the boys was so shocked, and when he came out, he grabbed me around the waist and said, 'thank you, thank you'."

"Just before 5:00 a.m. the Burlington Fire Department began receiving 911 calls reporting a fire in an upper unit of the stacked townhouse complex," said a news release issued Saturday by the Burlington Fire Department.

The complex is located at 2039 Walkers Line.

When firefighters arrived, they saw heavy smoke and flames coming from a unit at the complex's rear.

People had already started to evacuate, but firefighters did help some people leave their units. In one case, they helped small children whose "parents were sound asleep even though the fire was raging a couple of units away," Ben Rotsma, the Burlington department's fire prevention officer, told CTV Toronto.

Some firefighting units from Oakville and Hamilton helped fight the fire and provided backup for the Burlington stations, the release said.

Rotsma told ctvtoronto.ca that three firefighters were taken to Joseph Brant Memorial Hospital. Two required treatment for heat exhaustion, while a third either broke or sprained his thumb. Paramedics treated a fourth firefight on scene for heat exhaustion.

One youngster with asthma was taken to hospital on a precautionary basis, he said.

The residents of nine units may be able to return home tomorrow, Rotsma said.

However, the residents of the remaining nine units are going to be homeless for "a substantial period of time," given the heavy damage to their homes, he said.

Rotsma pegged the total damage to be in excess of $1 million.

An investigator with the Ontario Fire Marshall's office arrived Saturday afternoon to look into the cause, he said, adding the unit where the fire started was occupied at the time.

"Nothing's been ruled out, but we haven't keyed in on anything specific either," Rotsma said.

Local social agencies will help affected people find temporary housing while their units are repaired.