Investigators were unsure exactly how the shot was fired during the confrontation with the usher, who was pistol-whipped and suffered significant injuries.
"He's the hero," Anderson said. "He's the person that stopped this madness, and so we're very, very grateful to him."
Police said the usher then fetched his own legal firearm from a parked vehicle outside the church and used it to hold the gunman until officers arrived.
The gunman was identified as a 26-year-old from the Nashville area.
One woman was found dead in the church parking lot, police said.
All the victims were over 60 and suffered gunshot wounds, except the usher who was younger and was clubbed by the gunman.
Nashville Mayor Megan Barry called the shooting at Burnette Chapel Church of Christ in Antioch, a neighbourhood of south-eastern Nashville, "a terrible tragedy for our city."
Most of the victims were being treated at Vanderbilt Medical Centre, the Nashville Fire Department said.
The church pastor and his wife were among the wounded, according to police and a religious school where the minister also works.
Bill Hunter, the church's former pastor, told the Nashville Tennessean newspaper at the scene that he had spoken with people who were inside the church.
"I'm just absolutely stunned," Hunter said. "I just can't believe that somebody would come in off the street and start shooting, but that seems to be what happened."
Nashville is known as the home of the US country music industry. Tennessee is an inland state in the south-eastern United States.
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"He's the hero," Anderson said. "He's the person that stopped this madness, and so we're very, very grateful to him."
Police said the usher then fetched his own legal firearm from a parked vehicle outside the church and used it to hold the gunman until officers arrived.
The gunman was identified as a 26-year-old from the Nashville area.
One woman was found dead in the church parking lot, police said.
All the victims were over 60 and suffered gunshot wounds, except the usher who was younger and was clubbed by the gunman.
Nashville Mayor Megan Barry called the shooting at Burnette Chapel Church of Christ in Antioch, a neighbourhood of south-eastern Nashville, "a terrible tragedy for our city."
Most of the victims were being treated at Vanderbilt Medical Centre, the Nashville Fire Department said.
The church pastor and his wife were among the wounded, according to police and a religious school where the minister also works.
Bill Hunter, the church's former pastor, told the Nashville Tennessean newspaper at the scene that he had spoken with people who were inside the church.
"I'm just absolutely stunned," Hunter said. "I just can't believe that somebody would come in off the street and start shooting, but that seems to be what happened."
Nashville is known as the home of the US country music industry. Tennessee is an inland state in the south-eastern United States.
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