VALLEJO, Calif. — Cellphone video has captured the moment a Vallejo police officer used a racial slur during a traffic stop, sparking an internal investigation into the incident. A witness provided CBS San Francisco with video of the traffic stop, which took place Saturday morning near Sonoma Boulevard in the city of Vallejo.

Leo Bruno says he recorded the incident from inside his home. He told CBS News that he heard the officer say the n-word. “It sounded pretty clear to me as I was filming, though some who’ve watched it have had a little trouble hearing it,” he said Sunday.

He says that he was reminded of the recent police shootings of black men in the U.S. “All the fatal shootings over the …