(CNN) They were responding to a report of a single bee sting. But their problem was about to get a whole lot worse.

A group of firefighters and police that were responding to a bee sting were attacked Thursday afternoon by a swarm of nearly 40,000 Africanized bees.

Three of the first responders were rushed to the hospital, while the others quickly shut down the block.

"I've been with the fire department 18 years now and responded to several bee incidents," Pasadena Fire Department Public Information Officer Lisa Derderian told CNN. "But never to this magnitude."

A block full of bees

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