OTTAWA – It was a busy weekend for Ottawa Fire crews, who battled several blazes across the city, including one in old Ottawa South that caused one million dollars in damage.

The charred remains of an house on Hopewell Avenue is all that remains after a blaze broke out Saturday night. On Sunday, fire crews were on scene trying to determine what sparked the blaze which also damaged three neighbouring houses.

Crews say the fire began at 128 Hopewell Ave.and soon the flames were licking through the roof, spreading the blaze next door.

Ottawa Fire believes the blaze started on the grass before extending to a tree and then the home.

Platoon Chief Jim Bloom says it took 70 firefighters to put the blaze out.

“One house is totally destroyed,” he said, gesturing to the crumpled two-storey house behind him.

Bloom said the second home, which is missing large chunks of the roof, may also be a write-off.

The whole block was evacuated and more than 1, 300 people were without power because of downed power lines.

Shortly after the blaze in old Ottawa south, crews responded to another call at 250 City Center, where they found pallets and debris on fire behind the building.

The flames spread to behind the back door, then between the wall, before the sprinkler system kicked in and extinguished the fire.

Ottawa fire told 1310News, two units were damaged from smoke.

This all happened as 18 emergency vehicles and 40 firefighters remain on scene of a smouldering forest fire near Moodie Drive and West Hunt Club Road.

Three firefighters were treated for heat related illnesses Saturday, two had to be taken to hospital.

District Fire Chief Glenn Dollan told 1310News, firefighters removed the lining from their pants Saturday to help keep cool.

The blaze broke out Thursday afternoon and may continue to smoke for at least a week.

Marc Messier with Ottawa Fire said it won’t take much for the blaze to restart.

“If we get a sudden change of wind, or an increase of wind it could cause us a problem,” Messier said. “All kinds of things can happen. It just takes one ember to drift off and land in another area that’s very dry and this thing could set off again.”

Not only were fire crews battling the flames from the ground and air, but they had to deal with the sweltering hot temperatures Friday. Messier explained the plan to keep everyone out of the heat.

“There haven’t been any reports of any firefighters injured. A lot of them are obviously starting to feel the effects of the heat,” said Messier. “We’re telling them if you start to feel it come on out and let’s take care of it or get them back to stations so we can bring in fresh crews.”

Crews expect to remain on scene for a few more days.

The blaze is estimated to have leveled an area of about 40 hectares and although the cause isn’t officially known,  Messier believes without any recent lightning it was most likely caused by a discarded cigarette or intentionally set.