COVINA ( — An attack by a swarm of killer bees has left one dog dead and another seriously injured in Covina, according to reports Wednesday.

KNX 1070’s Jon Baird reports the attack occurred Sunday night after Heather Umphenour and her family returned home and found their two German Shepherd-mixed rescue dogs in the backyard covered with bee stings and surrounded by hundreds of dead bees.

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“There were dead bees all over the ground and … one dog was in shock,” said Umphenour.

One dog, Luna, died from her injuries, while her brother Wolf is still under veterinary care at the Inland Valley Emergency Pet Clinic, the San Gabriel Valley Tribune reported.

Wolf, who was stung primarily on his face, had swollen eyes that blocked his sight until Tuesday, pet clinic Medical Director Jeff Patlogar said.

Umphenour said the attack has devastated her family.

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“They cried themselves to sleep,” she said. “It’s really hard.”

A family friend set up a GoFundMe page to help cover the veterinary costs, which are expected run about $6,600. The effort has so far raised about $760.

Known as “killer” bees, most wild honeybees in the San Gabriel Valley are hybrids of European and African strains, according to the San Gabriel Valley Mosquito and Vector Control District.

“I would think it’s highly unusual for a swarm of bees to sting a person or an animal,” said Kenn Fujioka, the district manager of the San Gabriel Valley Mosquito and Vector Control. “Swarms of bees are not defending honey. They’re not defending their young and so they have no reason to seek out and attack.”

But late Wednesday, CBS2 spotted L.A. County agricultural inspectors looking for bees in the area. Although they wouldn’t comment on camera, they told CBS2’s Amy Johnson that they located a nest 100 yards away.

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