A driver looking at his GPS hit another car, causing a chain reaction on northbound Interstate 5. south of Via de la Valle for several hours Saturday evening.
The multi-vehicle crash caused heavy traffic in an area already congested by San Diegans heading to the San Diego County Fair.
The crash happened around 7:45 p.m. and blocked the right two lanes of the freeway, California Highway Patrol officers said.
There are no serious injuries, but it is unclear how many vehicles were involved.
Traffic is no longer congested in the area.
No other information was immediately available.