CAMPBELL — Police are looking for a driver who ran into a group of San Jose Bike Party bicyclists over the weekend and fled after injuring two riders, according to the Campbell Police Department.

A group of riders associated with the bike party, a South Bay tradition that attracts upward of 5,000 riders every third Friday of the month, was eastbound on West Campbell Avenue when a dark-colored Honda sedan drove into them near Carlyn Avenue around 1 a.m. Saturday, according to a witness and police.

Two riders, a 20-year-old woman and a 32-year-old man, were injured in the collision, Campbell police Capt. Charley Adams said. The driver did not stop and sped away, last seen southbound on Winchester Boulevard.

One witness said that, right after the collision, the driver turned off the headlights and sped off but not before leaving behind pieces of a broken right mirror and headlamp.

The female bicyclist was taken to a hospital with fractures to her skull and hip, along with a broken ankle and severe bruises, said a relative who was also on the ride. The male rider reported pain but declined medical treatment.

The same night, a Santa Clara County sheriff’s helicopter was called about 11:45 p.m. to a parking lot at Homestead Road and Lafayette Avenue near Santa Clara University, where its spotlight and PA system were used to break up a crowd of bicyclists that numbered in the thousands, sheriff’s Sgt. Kurtis Stenderup said.

Witnesses criticized the response as heavy-handed given the generally peaceful — albeit loud — nature of the bike party. Stenderup said the crowd was just too large for the property. He also said someone in the crowd shone a green laser at the helicopter but that deputies on the ground could not track its source.

Anyone with information about the hit-and-run can contact Campbell police Sgt. Dan Livingston at 408-866-2710.

Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga.