(Reuters) - A man wearing a wig and fake beard raised suspicion when he walked into a church service in Texas before opening fire with a shotgun and killing two people, a volunteer security guard who shot the assailant said on Monday.

The victims of Sunday’s shooting, identified as Anton Wallace, 64, of Fort Worth and Richard White, 67, of River Oaks, were also members of the civilian security force at West Freeway Church of Christ, the state’s attorney general said.

Jack Wilson, the head of the security detail, fired a single shot that took down the gunman, who has been identified by authorities as Keith Thomas Kinnunen, 43, of River Oaks.

Wallace was serving communion at the church in the Fort Worth suburb of White Settlement and was approached twice by the suspect in the moments before the gunfire rang out.

“When he sat back down the second time, shortly after that, he stood up, turned, and produced a shotgun,” Wilson told NBC News.

Wilson and White began “drawing our weapons. Richard did get his gun out of the holster. He was, I think, able to get a shot off, but it ended up going into the wall. The shooter had turned and shot him and then shot Tony and then started to turn to go toward the front of the auditorium,” Wilson told NBC.

“I fired one round. The subject went down.”

Keith Thomas Kinnunen, identified as a shooting suspect at a church in White Settlement, Texas, poses for an undated police booking photo released by the Tarrant County Sheriff's Office in Fort Worth, Texas December 30, 2019. Tarrant County Sheriff's Office/Handout via REUTERS.

Kinnunen was not a regular at the church and raised suspicion when he walked in wearing the wig and fake beard that he kept adjusting, Wilson said.

The reason for Kinnunen’s actions are unclear. State Attorney General Ken Paxton told a news conference that the gunman may have been mentally ill.

TRUMP PRAISES ARMED ‘HEROES’

The attack and response by armed civilians were likely to further inflame a nationwide debate over gun violence ahead of the 2020 presidential campaign.

“Our prayers are with the families of the victims and the congregation of yesterday’s church attack,” President Donald Trump said on Twitter.

“It was over in 6 seconds thanks to the brave parishioners who acted to protect 242 fellow worshippers. Lives were saved by these heroes, and Texas laws allowing them to carry arms!,” Trump said.

Local TV station NBC DFW, citing unidentified law enforcement sources, said Kinnunen had a criminal record that included charges of aggravated assault with a deadly weapon in 2009. A Texas Department of Public Safety spokeswoman declined to comment.

Texas allows concealed carry in places of worship under a law that took effect in September. It was passed following a shooting at the First Baptist Church in Sutherland Springs, Texas, in 2017 that killed 26 people.

Paxton encouraged other states to allow citizens to carry concealed weapons for defense in case of active shooters.

Wilson had previously trained other churchgoers to use firearms, and had his own shooting range, Paxton said.

But gun control advocates and some religious leaders have argued such laws have no place in houses of worship.

“Instead of looking for a success story in a tragedy, lawmakers should be talking about how they can prevent gun violence in the first place,” said John Feinblatt, president of Everytown for Gun Safety.