UPDATED AS OF 6:27 P.M.

BIG BEAR (CBSLA.com) — A burned-out truck owned by triple murder suspect Christopher Dorner was found in the San Bernardino mountains Thursday.

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The Nissan Titan, discovered on a dirt service road between Bear Mountain and Snow Summit resorts, was spotted around 8:35 a.m., approximately seven hours after Dorner allegedly fired at officers, killing one and critically injuring another in Riverside, San Bernardino County Sheriff’s officials said. A third officer in Corona suffered a graze wound.

Dorner, 33, is also wanted by Irvine police in the murder of an engaged couple on Feb. 3.

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San Bernardino County Sheriff’s deputies are on the scene.

The Bear Valley Unified School District was placed on lockdown.

“As a precautionary measure, we have called a district-wide lock down of all our facilities at 12:25 p.m. We don’t believe there is an immediate danger… we do this as a precaution for the safety of our students and staff,” Assistant Superintendent Walter Con said in a statement.

Bear Mountain Ski Resort is also closed while authorities use the parking lot as a command post.

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Snow Summit remained open to the public.