The shooting occurred at about 8:20 a.m. on southbound I-680 just north of the Livorna Road exit in the Alamo area. The freeway was closed in both directions and officers conducted their investigation at the scene.
The CHP reopened northbound lanes of I-680 around 1 p.m. Southbound lanes remain closed, but it is hoped lanes will reopen by 5 p.m.
The incident began when the CHP officer approached the suspect during a traffic stop. According to Contra Costa County Sheriff's Department spokesperson Jimmy Lee, the suspect opened fire at the officer, at which time a second CHP officer fire upon the suspect.
CHP Sgt. Diana McDermott said both the officer and the suspect were critically injured and were taken to hospitals. Neither the officer's nor the suspect's identity has been released.
Earlier in the day, investigators had been looking for the driver of a black 1998 Nissan Maxima. A spokesperson for the Contra Costa County Sheriff's Department said the driver has been located and it was determined she was not involved in the incident.
The suspect was the sole occupant of the car. No other suspects are being sought at this time.