Garcia said at a news conference that the driver attempted to make a left turn down a street when he collided with Katherman on his motorcycle.
A witness pulled over to assist Katherman and used his police radio to call for help. The officer was transported to Regional Medical Center where he was later pronounced dead.
The unidentified driver of the minivan stayed on the scene and was cooperating with police. Garcia said the man wasn’t in custody and it didn’t appear drugs or alcohol played a factor in the crash.
San Jose Mayor Sam Liccardo released a statement sending his condolences to Katherman’s family.
“Heroes lift us all through their sacrifice, compelling us to be our best through their example,” Liccardo said. “Mike Katherman was that hero, performing his noble duty to serve and protect until his last moments. I ask our residents to join in sending our prayers and thoughts to Mike’s wife, his sons, his family and friends, and the entire SJPD family during this time of grief.”