HESPERIA, Calif. - A swarm of Africanized "killer" bees attacked and killed three dogs when a hive was disturbed by a falling tree branch in a fenced backyard.

The owner of the three mastiffs - a male, female and a puppy - was also stung repeatedly while attempting to save the dogs, authorities said. The homeowner, whose name wasn't disclosed, went inside the house to escape the bees.

The bee hive in a stucco fence was disturbed by the falling tree branch on May 7, animal control supervisor Tony Genovesi said. The female dog weighed about 100 pounds, the male 90 pounds and the puppy 20 pounds.

Bee samples sent to San Bernardino County Vector Control confirmed they were Africanized honey bees, city spokeswoman Kim Summers said.

"They're very aggressive, and where other bees will chase you and leave, these will chase you a quarter-mile or more," Summers said.

About 90 percent of the bees in San Bernardino County desert areas are now Africanized honey bees, county Vector Control Program supervisor Joe Krygier said.