Los Angeles police are on tactical alert as they search for an ex-officer suspected of twice opening fire on officers after being named as a double-murder suspect.

Christopher Dorner (KABC TV)

Police Cmdr. Andrew Smith says the department has taken such protective measures as reassigning motorcycle officers to cars.

Fired officer Christopher Dorner is suspected of killing a Riverside officer and wounding another early Thursday, shortly after shooting at two LAPD officers in the nearby city of Corona. One LAPD officer was grazed.

The manhunt began after Dorner was named as a suspect in the weekend killing of a couple. One victim was the daughter of a former police captain who represented him during disciplinary proceedings that led to his firing.

Dorner wrote a manifesto pledging to bring "warfare" to the LAPD.

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