Ice and snow on the roadway is creating a traffic nightmare for holiday travelers near the Cajon Pass, with one crash causing all lanes to be closed in one direction in an area of the major thoroughfare.
Wintery conditions that also include rain have caused numerous accidents on the 15 Freeway near the 138 Freeway, according to the California Highway Patrol and National Weather Service.
"Be careful if you're driving!" San Diego area weather service officials advised in a tweet.
The CHP reported at least four crashes along the 15 Freeway since 6:35 a.m., but none of them involved major injuries.
All lanes of the northbound side of the highway were closed at Oak Hill Road after a multi-vehicle crash reported about 6:35 a.m. The crash began as a solo vehicle spinout, but soon 10 vehicles were involved. A SIG Alert was issued about 8:40 a.m., but the roadway was reopened about 10 a.m.
KTLA's Jennifer Thang contributed to this story.