(CNN) A California sheriff's deputy responding to a report of marijuana theft was shot and killed Wednesday, authorities said.

"Early this morning we lost one of our heroes," El Dorado County Sheriff John D'Agostini said.

Deputy Brian Ishmael "immediately came under fire" while responding to the call at a residence in Somerset, the sheriff's office said.

An off-duty San Joaquin County sheriff's deputy was on a ride-along with Ishmael and returned fire from the patrol car.

"He did his best to save Brian," Sheriff D'Agostini said.

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