An unusual type of storm nicknamed an "insider slider" blanketed Southern California mountains with up to 3 feet of snow and even coated desert areas with white.

Children built snowmen and had snowball fights in low-lying towns such as Murrieta in Riverside County, where Chris Sousounis said he was told it would never snow when he moved there from Chicago.

"Somebody lied," he said as he swept piles of snow off his pickup truck.

The weekend storm was tapering off Monday, although an additional 6 inches fell in some mountain communities.

The storm developed in British Columbia (search) and swept into Nevada before reaching California. It was called an inside slider (search) because of its rare track into Southern California from the northeast instead of the typical route off the Pacific Ocean.

"This happens about once every 10 years, and when it does, it's bad," said Ivory Small, chief science officer for the National Weather Service (search) in San Diego. "You get about every type of weather. ... These systems are tricky to predict."

Up to 3 feet of snow was reported in the San Gabriel and San Bernardino mountains east of Los Angeles.

Snow closed Interstate 15 through the Cajon Pass (search) northwest of Los Angeles for about five hours Sunday morning. Snow and ice also closed several roads in San Bernardino County, said California Highway Patrol dispatch supervisor Doug Showalter.

As much as a foot of snow covered desert areas of northern San Bernardino County, and 6 inches fell in desert communities such as Yucca Valley and Twentynine Palms. Lake Elsinore, southeast of Los Angeles, measured 3 inches.

Strong wind in Irvine toppled a tree onto a home, and some of the occupants suffered minor cuts and bruises.