The collision happened Sunday morning at the intersection of 5th and Howard streets. That's the same site of a more infamous crash back in June, where the firefighter driving was arrested for DUI.
"It was pretty noticeable," Jim Bettencourt said. "It was a large thud, like something had really made solid impact.:
Bettencourt heard the collision between a San Francisco Fire Department ladder truck responding to a call, and a Mercedes station wagon. Greg Wozniak saw it.
"I heard the siren and I turned around like this and I saw the car and boom! It happened that fast, it was quick, crazy," Wozniak said.
The impact of the collision spun the car around. A firefighter riding in the front cab of the Station One ladder truck was injured and sent to the hospital along with a passenger in the Mercedes. Both injuries were not serious.
"They had their sirens and lights on," SFPD Lt. Julian Hill said.
Police say the car heading west on Howard failed to yield to the fire truck driving north on Fifth.
"It appears that the Mercedes, a civilian vehicle, actually failed to stop for the fire truck," Lt. Hill said.
Accidents involving Station One fire trucks have happened at the same intersection before.
The ABC7 News I-Team first showed you a crash last June captured by security camera. A ladder truck responding to a call raced through a red light and collided with a motorcyclist, throwing the rider into a hydrant and seriously injuring him.
The firefighter driving left the scene and was later arrested on suspicion of DUI. He has resigned, but the investigation is still ongoing.
The same surveillance cameras, which captured that crash, likely taped Sunday's collision too.
But it appears this accident was not the fault of the first responders. The firefighter driving at the time tested negative for drugs and alcohol.
The emergency call this ladder truck was responding to on Sunday was handled by another engine company.