The way I understand it, he stabbed / murdered the three in his apartment first, then went out and shot and ran over others and murdered 3 more before committing suicide. http://www.mirror.co.uk/news/world-news/california-shooting-first-pictures-elliot-3605188
He also shot and injured quite a few. If you put the SB Sheriff’s details on a map, it becomes clear the whole thing took place within about a mile of his apartment.