The fire truck was en route to a call and traveling on Highway 288 near Highway 59 around 2 a.m. when the SUV, driven by former linebacker Brian Iwuh, slammed into the back of it.
The firefighter and Iwuh were both taken to the hospital.
The firefighter was said to have non-life threatening injuries. Iwuh's condition was not known. He was not wearing a seatbelt.
Iwuh played for the Jacksonville Jaguars, Chicago Bears and Denver Broncos.