One of those victims was identified as 28-year-old Ray Anthony Hutson Jr., of North Richmond, sheriff's spokesman Jimmy Lee said.
Richmond police responded to the first shooting at about 8:30 p.m. near the intersection of Ohio Avenue and South 39th Street, Richmond police Lt. Bisa French said.
Arriving officers found a man suffering from gunshot wounds. He was taken to a hospital and is expected to survive, French said.
Just before 10:30 p.m., the Contra Costa County Sheriff's Office received word of a fatal shooting in the 100 block of West Ruby Avenue in unincorporated North Richmond, sheriff's Lt. Vic Fernandez said.
Hutson, who was in his 20s, was found lying on the sidewalk. He was pronounced dead at the scene, Fernandez said.
A second victim, also man in his 20s from North Richmond, was taken to a hospital by helicopter. Lee said this morning that the second man was reported to be in critical condition.
Then, shortly after 11 p.m., Richmond police responded to a homicide in the 3200 block of Center Avenue. A 19-year-old man was shot and killed in his car as he was preparing to leave after visiting friends in the neighborhood, French said.
The last homicide was reported at the intersection of MacDonald Avenue and First Street at about 11:15 p.m., she said. A 27-year-old man was fatally shot, and another man also suffered injuries that are not believed to be life-threatening, French said.
It is too early to tell whether any of the shootings are related, French said. Investigators are interviewing witnesses and gathering evidence at the various crime scenes, she said.
"We're working with Richmond police to see if there is any possible connection with their shootings and to develop information on who did this," Fernandez said.
The Richmond Police Department and the Contra Costa County Sheriff's Office have not arrested any suspects in connection with the shootings.