About 600 people remained without power Sunday morning following powerful monsoon thunderstorms that rolled through Yuma.

©The Republic
Lightning flashes above Maricopa, Ariz. Saturday night.

The storms knocked out power to 9,600 people starting after midnight, said Arizona Public Service spokeswoman Donna Phipps.

Some of those people were without power for less than an hour, and 9,000 people had their electricity back on by Sunday morning. Another 200 were expected to get their power back on in the morning, but Phipps said it could take the better part of Sunday for the 400 other people.

"This was just one of those brutal monsoon storms," she said. "They come in and just hit you and go on about their merry business ... You could see it coming in and it was like, 'Oh boy, this is going to be a nasty one."

Leslie Wanek, a forecaster with the National Weather Service in Phoenix, said sustained winds were at 39 mph, with the highest gust clocked at 84 mph at 12:28 a.m.

"This was a big, bad one," Wanek said, adding that the wind speeds were "pretty incredible."

The American Red Cross opened a cooling center at Gwyneth Elementary School to help those without power get relief from the heat.

Last week, about 2,300 people in Coolidge went for two days without electricity as temperatures outside reached 110 degrees. A thunderstorm with winds up to 60 mph caused the outage after knocking down 11 power poles there.