Sgt. Kevin Bartlett said the toddler was shot three times, once in the hand and once in the torso. He said does not recall where the third bullet struck.
Police have said the boy's condition is more serious because of his small size and the number of times he was hit by the gunfire. He is at Children's Hospital in Oakland.
A $1,000 reward for information about the suspect has been offered through Crime Stoppers at (707) 644-STOP and the reward is expected to increase, Bartlett said.
The shooting happened around 4:50 p.m. at 1525 Lorenzo Drive across the street from the Dan Mini Elementary School. Witnesses said a man on a black motorcycle similar to a Kawasaki Ninja stopped and fired more than 20 rounds at the victims.
The rider was wearing a black motorcycle jacket, dark colored pants and a full-face helmet, police said. The motorcycle has a blue stripe on the gas tank.
All four victims were hit multiple times and police said the shooting is not considered a random act. The wounded were listed in serious condition Thursday.
Bruce Williams, 20, Lamar Williams, 19 and Eric Hamilton, 20, were taken to local hospitals.