Rain, hail and snow fell Monday as Southern California saw its first significant storm of the season.

Lightning flashed and thunder pounded as the storm front swept across the region in the middle of the night, unleashing downpours followed by bands of rain that continued throughout the day.

“The good news was the front was moving quickly which prevented any serious flooding from occurring,” the National Weather Service’s Los Angeles region office said. More than 1.5 inches of rain fell in downtown LA, while some areas saw more than 2 inches.

Localized roadway flooding and many traffic accidents were reported, and authorities along the coast cautioned potential beachgoers that water would likely be contaminated by bacteria, chemicals and trash washed down drains, creeks and rivers.

Firefighters used an inflatable boat to rescue a man and woman stranded by stormwater on a small island in the middle of the Los Angeles River north of downtown. Two people were also rescued from rushing water in Santa Ana. 

Snowfall accumulations in the region’s mountains were expected to range from 6 inches to 12 inches at elevations above 5,000 feet. Chains were required on some mountain routes east of Los Angeles after vehicles got stuck in snow and traffic was backed up for miles. 

The system also brought snow to the Sierra Nevada and showers to parts of Northern California on the heels of a Christmas Day storm.