The downpour prompted the shutdown of U.S. 60 in Tempe, Ariz., but that closure has since been lifted. State Route 88 northeast of Apache Junction and state Route 238 west of the Pinal County community of Maricopa also were closed.
Nearly a dozen car crashes were reported at the height of the storm in Phoenix, Scottsdale and Paradise Valley, officials said.
Some of the worst flooding was reported in Apache Junction, where more than 2 inches of rain in nearby mountains turned washes into rapidly flowing, thigh-high rivers.
The water swept away several vehicles and stranded some people in their homes, officials said.
The Apache Junction Fire department rescued two people who were trying to cross a flooded wash in a pickup truck, Deputy Chief Mike Farber said.
Fire crews lowered a ladder from a fire truck and transported them to drier land.
Numerous homes in parts of Scottsdale were flooded and fire crews plucked three stranded people in two incidents, said Scottsdale Fire Department spokesman Battalion Chief David Folio.
In Pinal County, two 19-year-old men became trapped in a tree and were rescued by the Department of Public Safety's helicopter and the Pinal County Sheriff's Office.
They were stranded east of Apache Junction after their vehicle got swept away by rushing water.
In Phoenix, the Fire Department rescued two people who attempted to cross flooded washes in their vehicles, Capt. Larry Nuñez said.
"If you see the flooded wash, don't cross them," Nuñez said. "They're going a lot faster than people think they are, and they're a lot deeper."