Bees attacked two dogs in a back yard, killing one, and authorities were investigating to see if the insects were the aggressive, Africanized variety.

Each dog was stung more than 100 times Saturday.So-called killer bees have killed more than 1,000 people in South America, Central America and Mexico since a colony escaped from a laboratory in Brazil in 1956. They are easily provoked and tend to nest in places European honeybees don't go, such as near the ground.

Swarms of killer bees have been found in Pahrump, 60 miles west of Las Vegas. Boulder City is 25 miles south of Las Vegas.