More than a dozen vehicles were involved in a major pileup on the southbound Interstate-5 off-ramp near Balboa Park.
The crash happened just before 4 p.m. on the Pershing Drive exit, CHP officials said. Traffic was backed up to Old Town by 4.30 p.m., CHP officials said.
"Going out to a meeting, exited here off Pershing and saw up ahead that there was a bunch of cars piled up," said Julio Gonzalez. "I immediately went to slow down, but then when you start slowing down and your car's not slowing down, there's a problem with the road."
Officials said that 18 vehicles were involved in the incident. Police believe an oil spill from a car is the reason behind the accident. Several tow trucks at the scene loaded up some of the vehicles.
One person was taken to the hospital with minor injuries. There are no reports of any major injuries.