(CNN) -- Eric Dixon was watching his daughter act in a church production of the musical "Annie" on Sunday in Knoxville, Tennessee, when paternal pride turned to horror.
"We heard a loud boom. I looked up at my daughter on the stage and she was looking up at the lights and I figured a light blew up or something," Dixon said. "I looked up and then the second shot happened."
The 12-gauge shotgun blasts were the opening rounds of an attack that killed two people at the Tennessee Valley Unitarian Universalist Church.
Six people were wounded by gunfire. A seventh person was injured diving under a pew. Four patients remain hospitalized.
Tammy Summers, 38, and Linda Chavez, 41, were upgraded Tuesday from critical to serious condition, Debbie Barton, a nursing supervisor, said. Jack Barnhart, 69, remained in serious condition, and Joe Barnhart, 76, was in stable condition, Barton said.
Two other patients have been treated and released.
Jim Adkisson, 58, has been charged with first-degree murder. Police said in an affidavit that Adkisson admitted to the shootings and told police the church's liberal teachings prompted him to attack.
As the second blast echoed through the room, Dixon said, someone yelled "Get down!"
"I started to get down, but then I was like, well, what good is that going to do?" he remembered. "So I jumped over the pew in front of me and I ran in that direction."
Other church members were also rushing toward the gunman. Dixon saw one of the adults in the cast of the musical reaching for the shooter.
Jamie Parkey, who was near the front of the church, told WBIR-TV he pushed his mother and a daughter who was sitting with him under the pew.
"I looked up and saw that men were rushing [the shooter]. And the only thing I could think of is, the best way to stop this was just to help them stop him," Parkey told the station, a CNN affiliate.
Two church members were already there, wrestling to get the gun away from the gunman, Parkey told WBIR, and the group "basically dog-piled him to the floor."
"By the time I got there, there were two or three people already on top of him. He was pinned to the ground," Dixon said. "I ran around to where his face was and I could only see maybe about four inches of his face. But I was screaming at him, " 'Why? Why did you do this?' "
The man didn't answer, Dixon said.
One of the other church members yelled "Get the gun away!" and Dixon thought there might be another weapon besides the shotgun. He grabbed at the gunman and got hold of a container he described as like a rigid leather bucket, open on top.
"When I pulled on it, shotgun shells just strewed out all over the floor. And I looked in there and there wasn't any other gun in there," Dixon said. Police said later that 76 shotgun shells were recovered from the church, including three spent rounds.
Dixon went to find his daughter, who was safe. Police arrived and took custody of the man they identified as Adkisson.
Looking back, Dixon had a simple explanation for running toward the shooter. "I didn't think about it," he said. "I did know somewhere inside that if this guy didn't stop, then we were all dead."
The gunman apparently did not expect the quick response from church members.
Knoxville Police Chief Sterling Owen said Monday that Adkisson "expected to be there shooting people until the police arrived and he fully expected to be killed by the responding police," based on a letter the police recovered.
"Were it not by the hasty actions of some of the other people in the sanctuary, there may have been more fatalities, so we all need to be thankful for that," Owen said.
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