A big rig carrying propane overturned along the on-ramp to northbound Interstate 15 from West Bernardo Drive.
The crash was reported to the California Highway Patrol at 10 a.m.
The onramp and offramp to the highway were closed while emergency personnel helped with the cleanup, Caltrans officials said.
As of 2:30 p.m., the truck had been moved away from the area but crews were still cleaning up the roadway.
