SAN DIEGO - No one was injured today in a multi-vehicle crash that backed up traffic on a busy Rancho Bernardo freeway, according to the California Highway Patrol.

The accident, involving three to four cars, was reported at 4:40 p.m. on northbound Interstate 15, north of Bernardo Center Drive, the CHP reported.

There were no significant injuries to report, a San Diego Fire-Rescue dispatcher said.

However, traffic on the 15 was particularly heavy this afternoon because of the Miramar Air Show and the San Diego Chargers-Oakland Raiders football game that both ended at 4 p.m.

As of 5:19 p.m., tow trucks were having difficulty reaching the crash site because of the backup, the CHP reported.

A SigAlert was issued, meaning some lanes would be blocked for more than an hour.