The accident happened at a four-way stop at 128th Place and Halsted around 6:15 p.m.
Engine 62 was headed south on Halsted. A Nissan Maxima was going west on 128th Place when fire officials say the sedan entered the intersection, stopped, and then continued, attempting to clear.
"I heard the fire truck try to brake. But you could just tell that there wasn't too much time. You heard the boom," said witness Lamonte Fryer.
The fire department says the engine was on a medical run and had its lights and siren on. But some witnesses say they never heard the engine coming.
"The lights were on, but you didn't hear no siren. That's what the story is. There was no siren," said witness Alex Parker.
The fire department cut into the car and pulled six people out including three children. All were transported to hospitals in serious to critical condition.
Witnesses say the male driver was talking after the accident but the female front passenger was unresponsive.
"The girl was hurt. She was just slumped over. It's like the passenger side was pushed to the driver's side," said witness Christopher Shurn.
"Everybody was distraught. There was a firefighter, he was injured, and he was still trying to help," said Parker.
Four firefighters were also taken to Metro South Hospital though all are in good condition.
Neighbors say the intersection has long been problematic, in part because a fence along Halsted, they say, can block the view of traffic.
"Two to three accidents happened this year already right here. I've been here 35 years. I've seen over 10 to 15 accidents at this stop sign the same way," said Fryer.