Prosecutors have filed murder charges against a Northern California man accused of shooting and killing a police sergeant during a traffic stop.

Alameda County District Attorney Nancy E. O'Malley announced Friday that charges were filed against 21-year-old Mark Anthony Estrada in the death of Hayward police Sgt. Scott Lunger.

The complaint charges Estrada with murder of a peace officer, lying in wait and discharging a firearm from a motor vehicle.

Estrada remains jailed without bail, and it's not clear whether he has a lawyer who could comment on the charges.

Lunger was shot Wednesday after he stopped Estrada for swerving and driving erratically. Another officer shot back, striking Estrada.

That officer was not injured.

The 48-year-old Lunger had been with the department for 15 years.