In Fresno County, just north of Selma, the penny-sized hail blanketed Manning Avenue, which is where at least two drivers lost control.
First, an unknown vehicle hit a brown pickup truck, causing it to crash into an almond orchard.
Four people inside a BMW pulled over to help.
"They stopped to be Good Samaritans, rendering aid, and they ended up getting struck by an out-of-control vehicle on a wet, icy roadway," said Sgt. Bryan Hunt with CHP Fresno.
The road was too slippery for a white Jeep. It crashed into the people and the BMW, sending three people to the hospital with non-life threatening injuries.
Officers are searching for the vehicle that initially hit the pickup truck.
Overall the wet weather was mostly an inconvenience to people in the Valley. It flooded parking lots and puddles on the road.
The California Highway Patrol said it was a good reminder to drive safely.
"When there's inclement weather like this, whether it's snow, rain, hail, you need to reduce your speed. Make sure you leave yourself a good space cushion between you and the vehicles around you and make sure you get to where you're going safely," said Hunt.
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The CHP says in the case of the crashes near Selma with hail covering the road, a safe speed would have been 25 to 30 miles per hour.
They believe some of the vehicles involved were going as fast as 60.