Police said witnesses reported a white male shot at least twice at two black males who were running from him around 8 p.m. on June 29 in the 400 block of East L Street, Lt. Mike Daley said.
Police found two spent shell casings at the scene but none of the involved parties, Daley said.
One witness said the two black men ran across Military Street and jumped into a late model black Nissan Sentra with a rear spoiler, Daley said.
The car was last seen getting onto eastbound Interstate Highway 680 from East 5th Street, Daley said. The shooter may have fled in a truck and local hospitals did not report anyone with a gunshot wound, Daley said.
On July 3, someone fired shots into an apartment in the 1500 block of East 4th Street around 11:35 p.m., Daley said.
Police arrived and found a large group of intoxicated people at a party. Officers checked the apartment that was targeted but did not find any one who was injured, Daley said.
"In this case it appears as though an argument took place between one of the tenants in the apartment and someone who was asked to leave the party," Daley said.
The person who was asked to leave returned with three or four people and he shot three or four rounds from the stairway up toward the second-floor apartment, Daley said.
Police have a person of interest in that shooting but need more information to make an arrest, Daley said.
"These shootings are very unusual for our community and we need people to come forward to help us identify the suspects and, in one case, the victims," Daley said.
Anyone with information about the shootings is asked to call detective Kevin Rose at (707) 747-4252 or CRIME STOPPERS at (707) 644-STOP(7867), which offers a reward.