It happened around around 2:45 p.m. on the Tasman onramp to southbound Interstate 880.
Officials confirmed there is one victim with a gunshot wound.
The victim was shot in the left shoulder and taken to the hospital.
There was one other passenger in the victim's car, who was unharmed.
Investigators say the suspect was seen driving a black sedan. No further description is available at this time.
Investigators are still at the scene, with no ETA for reopening the roadway.
Drivers are advised to avoid using the Tasman onramp to southbound 880 or the southbound 880 offramp to Montague.