It happened at the Merced Street exit just before 3:30 am.
The California Highway Patrol says multiple vehicles crashed on the northbound side of the highway. It's unclear if anyone was hurt.
Crews have cleared the vehicles from the roadway, allowing the two left lanes to reopen. The right lane remains closed at this time.
The CHP says traffic is flowing, but drivers should expect some slowdowns in the area during their commute while authorities continue their investigation.
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