The shooting was reported at about 5:30 p.m. Thursday outside the apartment complex located at 201 Maine St., police Sgt. Jeff Bassett said.
The victims were near some steps in front of the "L" building at the apartment complex when a vehicle drove by and at least one suspect opened fire.
The girl was struck in the lower extremities by the gunfire and was taken to John Muir Medical Center to be treated for her injuries. The man suffered a grazing wound, and was taken to Sutter Solano Medical Center, Bassett said.
No arrests have been made in connection with the shooting, he said.
The suspect vehicle is described as a gray or silver sedan, possibly an Infiniti, that had three passengers. The suspects were all black males wearing masks, and one of the suspects had dreadlocks, Bassett said.
Police recovered 14 shell casings at the scene, he said.
Investigators are trying to determine a motive for the shooting, according to Bassett.
"The victims have no idea why they may have been targeted," he said.