They were wrong.
What they arrived to was upwards of 40,000 Africanized bees taking over a complete block: originating from a bee hive on the roof of a four-story Hampton Inn.
Some of the firefighters, along with a professional beekeeper, removed the hive and sprayed the bees with foam extinguishers and Co2. The bees either retreated when dusk hit, or were killed.
In the end, the aggressive bees stung seven people: three of which were first responders that were sent to the hospital (one firefighter was stung 17 times).
Source: CNN