SAN BERNARDINO, Calif. (KABC) -- Inland Empire residents should watch out for "half dollar size hail," flash flooding and lightning as a severe thunderstorm moves into the region, the National Weather Service said Sunday afternoon.
The severe thunderstorm warning was issued for San Bernardino and Riverside counties. The storm was observed around 4 p.m. 14 miles north of Indio, moving west at 15 mph.
The NWS said residents can expect the "half dollar size hail" to damage roofs, trees and vehicles, along with winds up to 60 mph.
The service also said flash flooding in some areas can be expected:
"For your protection move to an interior room on the lowest floor of a building.
Large hail and damaging winds and continuous cloud to ground lightning is occurring with this storm. Move indoors immediately.
Lightning is one of natures leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning.
Torrential rainfall is occurring with this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways."
Hundreds of lightning strikes have already been recorded in the region.
The flash flood warning is expected to remain in effect until 7:30 p.m.