Ashbrook interrupted a teen prayer rally in the Wedgwood Baptist Church, slamming his hand on a door to make his presence known. Spouting anti-Baptist rhetoric, he opened fire with a 9 mm semi-automatic handgun and a .380-caliber handgun. He reloaded several times during the shooting; three empty magazines were found at the scene. Seven people were killed, four of whom were teenagers (a 14-year-old boy, two 14-year-old girls and a 17-year-old boy). Three people sustained major injuries while four others received relatively minor injuries.
At Ashbrook's home, police found a pipe, end caps to enclose the pipe, gunpowder and a fuse. Ashbrook had thrown a pipe bomb into the church, but it exploded vertically, and did not injure anyone.
During the shooting, Ashbrook was confronted by a 19-year-old former football lineman, "Jeremy" Jeremiah Neitz, who recounted the ensuing conversation for the Houston Press:
I don't know why, but I just sat there, looking at him as he came toward me. When he got to within about five feet, he pointed one of his guns at me and just glared. I told him, "Sir, you don't have to be doing this." He told me to shut the hell up. Then he asked me what my religion was, and I told him I was a Christian, a Baptist. He said, "That sucks," and that it was "a stupid religion." [Neitz replied] "No sir, it doesn't suck. It's a wonderful thing. God put me on this earth for a reason. I'm certain of that."
Ashbrook fired several more rounds and yelled, "This religion is bullshit." Neitz replied, "Sir, what you need is Jesus Christ in your life." Neitz asked Ashbrook "What about you?" Ashbrook said, "F off," sat down and shot himself." Time Magazine described accounts of the confrontation as "unconfirmed" and possibly "pious invention", but the Houston Press wrote that the story had been confirmed, quoting the Fort Worth police detective who had interviewed Neitz: "Maybe he did frustrate Ashbrook with what he was saying. There's no way we'll ever really know. All I can say is that I'm impressed by what he did that evening. It was a very brave thing. You have to admire that."
Nine years before the shooting, Ashbrook's mother died. This reportedly sent him into a cycle of erratic and frightening behavior. Ashbrook lived for many years with his father, Jack D. Ashbrook. Across the street from the Ashbrooks' home, neighbors said they saw Ashbrook treat his father violently but were afraid to report it. Newspaper editor Stephen Kaye, whom Ashbrook had visited days before the shooting, described him as being "the opposite of someone who'd be concerned about", saying he "couldn't have been any nicer."
However, his neighbors had an entirely different view of him, describing him as strange and violent. Investigators at his house discovered that he had virtually destroyed the interior of his house - holes were bashed into the walls with crowbars, the toilets were filled with concrete, and the fruit trees growing in the backyard had been poisoned.
Police investigating the shooting could find no solid motive for the crime. In the months before the shooting, people who knew Ashbrook said he became increasingly paranoid, certain that he was being framed for serial murder and other crimes that he did not commit. He also feared that the CIA was targeting him, and he reported psychological warfare, assaults by co-workers and being drugged by the police. Just days before the shooting he voiced these concerns to a newspaper, saying "I want someone to tell my story, no one will listen to me; no one will believe me."
According to Houston-area writer John Craig, Ashbrook had ties to the Phineas Priesthood and Christian Identity, both of which view mainstream Christianity as an enemy.