Cars were seen partially submerged near the Ontario International Airport at Grove Avenue and Francis Street in the Inland Empire. Ontario police temporarily shut down the intersection as drivers were being rescued from the watery mess.
Other areas in Ontario, including the intersection of Walnut Street and Cucamonga Avenue, also saw heavy flooding conditions.
THIS JUST IN: Street flooding near Walnut St and Cucamonga Ave in Ontario pic.twitter.com/baylgouxa9— ABC7 Eyewitness News (@ABC7) May 7, 2016
A roof was seen collapsed due to the damaging wet weather at a Classic Containers business location in the 1700 block of S. Hellman Avenue.
THIS JUST IN: Scene of roof collapse at Classic Containers in 1700 S. Hellman Ave in Ontario pic.twitter.com/oMNZ98U4m9— ABC7 Eyewitness News (@ABC7) May 7, 2016
People were seen from the large hole in the roof of the warehouse mopping up the business and attempting to move the water out.
THIS JUST IN: Flash flood warning issued in San Bernardino County until 7:15pm— ABC7 Weather Center (@abc7weather) May 7, 2016
A flash-flood warning was issued for San Bernardino County until 7 p.m. The cities affected included Ontario, Chino, Chino Hills, Upland, Montclair, Rancho Cucamonga and Fontana.
MORE: Get the latest weather updates for Southern California.
It was also a rainy, traffic-nightmare on the 5 Freeway as a mudslide shut down part of the Grapevine.
The muddy runoff was seen going down the northbound lanes, near fort Tejon Road around 4:45 p.m. Many drivers captured the seen of rocks and debris, and patrol cars guided vehicles through the mess.
The 5 North was temporarily shut down for miles, trapping many for hours in standstill traffic.
"We left about 4:30 p.m. or so, and we were stuck for maybe another four hours in traffic...," said one driver.
All lanes on the 5 Freeway were back open around 9 p.m., according to the California Highway Patrol.