Dust storms swept across central Arizona late Monday, prompting officials to briefly ground flights at Phoenix Sky Harbor International Airport and leaving tens of thousands of customers without power.

The Federal Aviation Administration announced the ground stop on flights at the airport just before 6:30 p.m. local time, citing the storms. It lifted the ground stop about an hour later.

As the airport resumed operations, it was experiencing delays of 15 to 30 minutes for departing flights, an airport spokesman said at about 8:30 p.m.

More than 40,000 customers were without electricity in Maricopa County, which includes Phoenix, late Monday, according to the power-monitoring site poweroutage.us.

More than two million people in and around Phoenix were under a dust storm warning on Monday afternoon, as the National Weather Service warned of low visibility and strong winds. The warning was lifted in the evening as the dust moved north.

At about 7 p.m. local time, dust was blowing over Black Canyon City, north of Phoenix, according to the Weather Service. The agency urged motorists not to drive into the storm, warning of poor visibility and strong winds of more than 50 miles per hour.

This is a developing story.