An overturned big is stalling traffic for several hours Tuesday morning, and CalTrans and CHP officials are working to clear the traffic on the northbound side of Interstate 5.

Traffic is backed up for several miles after a big rig driving northbound on I-5, north of Calgrove Blvd. in the right lanes of the freeway overturned for an unknown reason.

“I-5 northbound was fully shut down for approximately 15 minutes to facilitate a cone and flare pattern,” according to an email from Officer Josh Greengard of the California Highway Patrol, “and afterward the right two lanes were opened.”

The expected duration of the left two  will be approximately 5-6 hours to facilitate the clean up of the semi truck-trailer load.

The road was expected to be cleared by approximately 11 a.m., according to a CHP report.

Alcohol and drugs were not a suspected factor in this incident. No arrests have been reported, according to CHP officers.