A man who witnessed the fatal shooting of a Brazos County constable and a civilian bystander in a College Station neighborhood last summer is talking publicly about what happened for the first time.
His identity wasn't released by investigators because he wanted to remain anonymous at the time.
But now we're hearing first hand how he fired back at the gunman, and possibly saved the lives of others.
Police scanners told the story that day.
"There is an active shooter. We have 2 officers down that we know of and 1 female that's been shot in her vehicle."
August 13th, 2012 turns into a horrific day on the corner of Fidelity and Highland Street in College Station.
Brazos County Constable Brian Bachmann is attempting to serve a notice for Tres Caffall to appear in court for failure to pay rent.
Caffall opens fire with a rifle, killing Constable Bachmann.
Scanner traffic: "Do we have a description of the shooter?"
But the 35-year-old Caffall, who his family believes had some mental issues, didn't stop there.
He starts firing at people in the neighborhood with a number of weapons, including an assault rifle and a sniper rifle.
Police scanner: "Can we get a second ambulance to stage in the area in case we have multiple victims?
"My adrenaline was going so high."
One person sees almost all of it.
Tim Irvin is helping his girlfriend, Barbara Holdsworth, move her daughter, a Texas A&M student, out of a rental house just 60 yards from where Caffall is taking aim at anything that moves.
Irvin is in the direct line of fire and tells nearby students to get inside or take cover.
He says, "And I know it sounds a little corny, particularly to non-believers, but when I got out of my car, I heard for the first time I believe ever, a higher power saying, you go do your thing and I'll do mine. And I know not where that voice came from, but I know that it was outside of me. So I just grabbed my cell phone, called 911, grabbed my pistol, and tried to just keep moving."
Barbara Holdsworth had been following Tim in her own car.
"When she pulled in she had a very dazed look on her face but I couldn't tell if she had been hit at that point. She tried to put her car into park, but put it into neutral, maybe because she just didn't have the strength, and that's when she rolled out into plain view of the shooter."
Irvin knew he had to draw fire away from Holdsworth, who was critically injured and losing a lot of blood inside her car.
He recalls, "I fired once, he turned towards me. He evidently knew that there was outside fire, and then I fired twice more, and that's when he directed his fire at me, hit the car that was behind me, a tree that was right there, he hit the house. And then I immediately layed down and rolled over to the edge of the fence and fired my last two rounds."
Meanwhile, civilian bystander Chris Northcliffe is walking down the street, not knowing the danger ahead.
Irvin says, "I had told him there was a shooter that was shooting at anything and everything. I just don't think he had time to take cover."
Northcliffe was shot and killed.
By now, Irvin believes Caffall has retreated inside his house to reload.
So he returns to Holdsworth's car and pulls her down in the seat.
"I just said just please, please try to stay awake and please don't go to sleep. You're too good of a person to go like this, let's just try to get through this together."
And then Caffall opens fire on Holdsworth's car again.
By now College Station Police arrive and begin taking fire from Caffall, and return fire. Three officers are wounded, but survive.
And then after the 25-minute shooting spree, Caffall is shot and killed.
Meanwhile Holdsworth is rushed to St. Joseph Hospital, and survives two gunshot wounds.
And as for the impact of Tim Irvin's initial 911 call, College Station Police Chief Jeff Capps says, "He was able to provide in that information that there were other people in the area. He was very instrumental to alert them, keep them behind cover so they weren't injured as well during the process."
But Irvin credits bystanders, and police, and E-R doctors and surgeons and nurses with saving lives.
"Those are the heroes. And I had wanted to remain anonymous. That's why the police asked that, for that very reason, because it wasn't about me. It was about a sick individual that could have taken more lives, and just by the grace, I was there to help protect, then that's great."