A swarm of Africanized bees in St. Petersburg, Fla., left one dog dead and another in emergency care Thursday morning.

Boss the pit bull and his best canine friend, Mama, apparently got loose from their home and wandered into a neighbor’s backyard, where they were attacked by the swarm of bees whose nest was in the home’s attic. Authorities believe the dogs’ barking attracted the swarm, which stung each dog more than 100 times, the Tampa Bay Times reports.

"Boss was in love with Mama," Fabian Guzman, 28, who owns the two pit bulls, said. "She has over 100 stings. They're not sure if she's going to make it."

An exterminator called to the scene estimates there are as many as 80,000 bees in the nest. They plan to carefully remove the hive at dusk when the bees are less active.

"It's a very large hive," St. Petersburg Police Lt. Dennis Bolender said. "At this point, we're not able to address the hive until after dark."

Guzman said he was walking out his front door Thursday morning carrying food for the dogs he had rescued two weeks earlier, when he saw they'd broken out of his screened-in porch. He saw Boss thrashing down the street engulfed in a swarm of bees. He ran over to help and got stung near his eye.

"I ran out there, tried to grab the dogs, got stung. Grabbed the water hose to get the bees off. We finally got the dogs out of there," Guzman told Fox 13.

Africanized bees were initially brought to Brazil by a geneticist in 1956 but later escaped, reaching Mexico in 1980, Texas in 1991 and Florida in 2005. Nicknamed “killer bees” for their aggressive behavior, they are more likely to attack when instigated and their numbers are more threatening than their venom, according to Dr. May Berenbaum from the University of Illinois Department of Entomology.

When an Africanized bee attacks, they are more aggressive because an entire colony participates in the attack. "If you can't escape, that's when the fatalities occur," Berenbaum told CBS News.

In Florida, Africanized bees are considered an invasive species and beekeepers are struggling to contain them. “Now they're here, and it's a huge problem," beekeeper David Gatley told ABC 7. Ninety percent of the bees I remove are Africanized,"  added Gatley, who removes two or three hives a day in Southwest Florida.

Don and Shirley Burns, the couple that owns the St. Petersburg home with the beehive, said they would have had it removed if they'd known it was there. But neighbors said they had seen bees around there before.

"I've been here 18 years, and it has been that way for 18 years," Tukevia Smith said. "I have small kids, and I have complained numerous times about the bees there."