Grande Prairie's fire department said all four homes were engulfed in flames when crews arrived early Wednesday.
"Two of the homes are completely destroyed, one is severely damaged and the fourth one had its roof completely burned off," platoon chief Barry Chorney said.
Occupants from one of the homes were awakened by their smoke alarm and were forced to flee the flames through a second-storey window. The fire department said one of the people was slightly hurt.
An unconfirmed report said the injury may have been a broken ankle.
Chorney said all four houses were occupied, but there was no word on how many people have been displaced.
"The damage is severe enough ... that they're not habitable, so they'll probably be torn down," he said of the houses. "It's up to the insurance companies, but based on experience, it's a fair bet that they'll be taken down and rebuilt."
If it had been a windy night, the flames could have spread further because of the close proximity of the buildings, Chorney added.
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