It happened near Southern Boulevard and Barretto Street in the Longwood section around 12:30 p.m.
The articulated bus was carrying more than a dozen passengers at the time of the crash.
One of the passengers said the impact was greater for those sitting in the front and caused people to fall out of their seats.
EMS transported five firefighters and 14 civilians to area hospitals.
Three civilians were evaluated on the scene but refused to be taken to the hospital.
Jumari Lantigua was walking down the street around 12:30 and says she saw it all.
"The fire department, they came from the corner, and they didn't stop at the light, they just went head on and hit the bus," Lantigua said. "The fire department truck was coming at a high speed."'
She said that didn't hear sirens on the truck and they didn't have lights on.
The truck was full of firefighters at the time of the crash.
Few other details were released.
This story will be updated as more information becomes available.
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