RIVERSIDE (AP) — Wildlife rehabilitation experts are working to keep two baby opossums alive after the mother was apparently beaten to death with a sharp rock.

The Press-Enterprise reports that the 2-year-old mother with two babies in its pouch was found in critical condition by a security guard outside an industrial building in Fontana on Monday.

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Karolyn Verville, who heads Sunshine Haven Animal Rescue & Wildlife Rehabilitation in Riverside, says the opossum died three days later.

She says a sharp rock with blood and fur on it was found near the opossum.

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Verville has been feeding cat milk replacement to the hungry babies, which she says tends to suit most wildlife.

Fontana police are searching for the attacker.

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