about what he had to do. and we're learning more about the gunman who did not survive the attack. abc's marcus moore is on the scene. >> reporter: tonight, six seconds of terror capturing the moments lives were shattered and dozens more saved. jack wilson, seen here firing a single shot, killing the gunman before he could harm anyone else. >> i don't feel like i'm a hero. i was doing what i needed to do to protect the people of the congregation. and i, you know, in the same scenario, i would do it again. >> reporter: the split-second decision stopping an attack that erupted in the middle of sunday morning service at the west freeway church of christ, near ft. worth. the church livestreaming the service. in the video, you see the alleged shooter, keith kinnunen, get up from the back of the room. he appears to say something to a deacon and then pulls out a shotgun. >> his left hand never was visible, so, i'm assuming at this point that the shotgun was, you know, was in his pocket, all the way up under his armpit.