Thousands of Phoenix-area residents and businesses, including a food bank, remained without power a day after a monsoon storm knocked down trees, damaged buildings and toppled a tractor-trailer on a freeway.

The area's two major utilities reported that more than 20,000 customers still had no electricity by midday Tuesday. About 70,000 homes and businesses had been in the dark immediately after Monday evening's storm.

The severe weather began moving through the area around sundown and swept across central Phoenix, Scottsdale and Tempe with lightning, winds of up to 65 mph and up to 1.5 inches of rain, according to the National Weather Service.

Flooding temporarily closed roads and freeway ramps, while high winds knocked over a tractor-trailer on Interstate 10, sending it crashing onto the hood of a car.

Dozens of traffic signals remained dark during Tuesday morning's rush hour and city officials said lights at about 50 intersections still were being repaired.

"Last night Mother Nature did a number on our city," Mayor Greg Stanton said.

Fire officials said that in a two-hour period, they received more than 400 calls for help — the number they normally receive in an entire day. Rescuers responded to a house fire started by lightning, motorists stranded in flooded streets, car crashes and other problems, but there were no reports of deaths or serious injuries.

More than 35 rooms at the Carl T. Hayden VA Medical Center had water damage Tuesday and hospital officials had to relocate patients to other rooms or transfer them to other facilities in the Phoenix metro area.

The Salt River Project said it expected to restore power to nearly all of its 2,100 remaining affected customers by Tuesday afternoon.

Arizona Public Service Co. said in a statement that it first focused on clearing downed lines and restoring service to essential facilities, then was concentrating on restoring major lines serving large numbers of customers.

APS said it had 21,000 customers without power as of early Tuesday afternoon, but it expected to have a majority of the outages fixed by early evening.

Several schools were closed Tuesday because they had no electricity.

The main warehouse of St. Mary's Food Bank Alliance lost power, and the nonprofit borrowed refrigerated trucks to move Thanksgiving turkeys and other perishables to a smaller warehouse and to recipient agencies.

As dripping water began to puddle on the floor of freezers Tuesday morning, workers used forklifts to move pallets of food into trucks backed up to a loading dock. Some dairy products were being left behind, partly because of expiration dates.

"We're going to lose stuff because it's too hot, but we're going to save as much as we can," spokesman Jerry Brown said. "This is a race against time."

At the Phoenix Zoo, workers used chain saws and cranes to cut up and haul away dozens of trees toppled by wind. Some fell into exhibits for camels, flamingos and other animals, but none was injured, according to officials who said the zoo also would be closed Wednesday for storm cleanup.

Phoenix Sky Harbor International Airport suspended takeoffs and landings for more than an hour and temporarily halted part of a shuttle train's operation Monday night. One gate at Terminal 3 was closed for cleanup and repairs after the top layer of part of a concourse's roof was blown off, resulting in water damage, airport spokeswoman Julie Rodriguez said.

The Federal Aviation Administration's website showed there were no significant delays Tuesday morning.

Strong rain and wind storms are common in Arizona during the state's monsoon, a regular season that usually runs from June 15 to Sept. 30. They typically strike in the late afternoon or early evening and often are accompanied by giant walls of blowing dust.