A fuel tanker overturned on the off-ramp from westbound Interstate 8 to Morena Boulevard Friday, spilling fuel onto the roadway.
The incident was reported shortly after 6 p.m., and authorities said a hazardous materials team was summoned to the scene to assess the fuel spill.
10News learned the tanker was a 3,700-gallon tanker that was carrying about 1,000 gallons of diesel fuel, and the crash caused at least 1,000 gallons to spill onto the road and 50 to 100 gallons into the river below.
Officials believe the fuel in the river will eventually make its way into the ocean.
The tanker's driver suffered minor injuries in the crash. No other injuries were immediately reported.
Both directions of Morena Boulevard remain closed between Linda Vista Road and Taylor Street as of 9 p.m.
The cause of the crash is under investigation, and cleanup is expected to last into Saturday morning.