A man accused of killing two people and wounding seven others with a shotgun during a church youth performance in Tennessee targeted the church because of its support of liberal social policies he loathed, police alleged Monday.

Investigators recovered a note from the SUV of the alleged gunman in Sunday's shooting incident at Knoxville's Tennessee Valley Unitarian Universalist Church, police chief Sterling Owen IV told reporters at a press conference.

"It appears that what brought him to this horrible event was his lack of being able to obtain a job, his frustration over that and his stated hatred of the liberal movement," Owen said.

Witnesses said some of the 200 church members in attendance wrestled the suspect to the ground after he pulled a 12-gauge shotgun from a guitar case and fired three times during the children's performance based on the musical Annie.

No children were hurt, but five people remained in serious or critical condition Monday. The dead included Greg McKendry, 60, a burly usher whom witnesses hailed as a hero for using his body to shield others from the gunfire.

"Greg McKendry was a very large gentleman, one of those people you might describe as a refrigerator with a head," church member Schera Chadwick said. "He looked like a football player. He did obviously stand up and put himself in between the shooter and the congregation."

"Intended to take a lot of casualties"

Owen said the death toll could have been much higher, as the gunman had 79 rounds of ammunition.

"He certainly intended to take a lot of casualties," he said.

The accused, Jim Adkisson, 58, is currently charged with one count of first-degree murder and was being held in custody, authorities said. More charges are expected.

According to investigators, Adkisson was an apparent stranger to the church, which promotes progressive social work, including advocacy of women and gay rights.

The Knoxville congregation also has provided sanctuary for political refugees, fed the homeless and founded a chapter of the American Civil Liberties Union, according to its website.

His neighbour, Karen Massey, described Adkisson as a quiet, but courteous man.

"A neighbour that if you needed something, you could ask him," Massey said. "He'd wave and be friendly, but he mostly stayed to himself."

With files from the Associated Press