Traffic is slowly moving heading north on Interstate 5, after being at a standstill for several hours Saturday.

23ABC viewers tell us, a big rig was overturned on the freeway, causing traffic on Vista Del Lago Road.

As of 9 p.m., traffic was at a standstill around Posey Canyon. 

The California Highway Patrol tweeted at around 6:30 p.m. that all northbound lanes on the I-5 were closed due to a traffic collision. 

Moments later, Caltrans tweeted that the far right lane was open and was causing a 90 minute delay on the freeway. Cleanup was expected to take around 4 hours.