It happened shortly after 4 p.m. at 7th Street and Girard Avenue. Police say the crew with Engine 29 was responding to a house fire near Front and Diamond streets, with lights and sirens active.
A witness says a car shot across the intersection. The fire truck tried to swerve out of the way but hit a woman driving a black Toyota.
According to the witness, the fire truck then bounced off the median, hit a parked truck and careened into a building.
The car, with heavy front-end damage, could be seen a short distance away.
Four firefighters were on board the truck at the time of the crash. Officials say all four were injured and two of them had to be pulled from the emergency vehicle.
Action News has learned that two of the injured firefighters have been identified as a 54-year-old man and a 41-year-old man.
All four firefighters were treated and transported to area hospitals. They were all released from the hospital Thursday night.
A woman driving in the Toyota was also injured. Her injuries do not appear to be life-threatening, according to Assistant Fire Chief Charles Walker.
The view from Chopper 6 showed the fire truck almost entirely inside the building.
On Thursday night, crews spent hours slowly removing the truck inch by inch. It was a long and slow process to safely remove the truck from the building while making sure the structure didn't collapse.
Officials believe at least one family lives inside the building where the crash occurred.
Walker says there are concerns that the building may be structurally compromised.
"L&I is here on location, along with the utility companies just to make sure that we have no gas leaks or anything of that nature," said Walker.
The investigation is ongoing.