About 1,407 Roy and Hooper homes were expected to be without power until Friday morning, due to a substation that went out of service.
Rocky Mountain Power spokesman Dave Eskelsen said the outage happened at a substation in west Roy around 6:30 p.m. As of 7 p.m., he said crews had not identified the cause of the outage. The company's website listed the cause as an equipment failure.
Eskelsen originally said the outage was expected to last for at least a couple of hours, adding it was hard to pinpoint an exact estimate without knowing the outage's cause. Rocky Mountain Power's website later listed the expected time of restoration as 7:30 a.m. Friday.
Temperatures in the area were in the high 90s throughout the day and were still around 90 degrees at 9 p.m.