KNOXVILLE, Tenn. — A gunman opened fire at a church youth performance yesterday and killed two people, including a man who witnesses called a hero for shielding others from a shotgun blast.

Seven adults were also injured but no children were harmed at the Tennessee Valley Unitarian Universalist Church. Members said they dove under pews or ran from the building when the shooting started. The gunman was tackled by congregants and eventually taken into police custody.

Jim D. Adkisson, 58, was charged with first-degree murder and was being held on $1 million bail, according to a city spokesman, Randy Kenner, who did not know if the suspect had retained an attorney. Authorities were searching Mr. Adkisson’s home in the Knoxville bedroom community of Powell, Mr. Kenner said.

The man slain was identified as Greg McKendry, 60, a longtime church member and usher. One church member, Barbara Kemper, told the Associated Press that McKendry “stood in the front of the gunman and took the blast to protect the rest of us.”

Linda Kreager, 61, died at the University of Tennessee Medical Center a few hours after the shooting, a Knoxville city spokesman, Randall Kenner, said.

Five people remained hospitalized, all in critical or serious condition. Two were treated and released. The gunman’s motive is not yet known. The church, like many other Unitarian Universalist churches, promotes progressive social work, such as desegregation and fighting for the rights of women and gays.