SAN DIEGO -- A collision on Interstate 805 set off a wave of other crashes early Thursday, sending a total of five people to the hospital, authorities said.

The crashes on the southbound side of the freeway, just north of Market Street, happened shortly before 2 a.m., according to the California Highway Patrol.

The first crash involved a vehicle pulled over for a flat tire being hit by another vehicle, CHP Officer Ray Scheidnes said. A drunken driver may have been involved in one of the crashes but it was not immediately clear which, he said.

Paramedics took two people to UCSD Medical Center, two people to Sharp Memorial Hospital and one person to Scripps Mercy Hospital, a San Diego fire- rescue dispatcher said.

At least two vehicles involved in the crashes were driven from the the scene before helped arrive, Scheidnes said.