Police responded to reports of multiple people shot Sunday night around 11 at Princeton Dr. near Dartmouth Ave.
Investigators say four carloads of young adults from South San Francisco were heading to Vallejo for a party.
When one car hit a curb and got a flat tire near the 200 block of Princeton Ave., the whole group pulled to the curb.
A neighbor warned the people they were in a bad area, and then heard shooting.
"There were about 25 gunshots or maybe 20, but it was a lot," witness Victor Maonjaraz said. "You couldn't even count them, how fast they were and how many there were. "Yeah, and that's pretty sad."
A 19-year-old man died at the scene.
Police say there appeared to be only one gunman inside the vehicle -- a white SUV with tinted windows.
Anyone with information about the crime is asked to contact Vallejo police at (800) 488-9383.
Anonymous callers can call Solano Crime Stoppers tip line at (707) 644-1867.
(Bay City News contributed to this report)