In this video grab churchgoers take cover while a congregant armed with a handgun (top left) engages a man who opened fire (top center) at a church in Texas on Sunday. AP

A gunman who killed two people during a Texas church service was fatally shot within seconds by armed congregants, said state officials, who hailed the state's gun laws that allow weapons in places of worship.

More than 240 people were in the West Freeway Church of Christ in the Fort Worth-area town of White Settlement during Sunday's shooting, authorities said.

In a livestream of the church service, the gunman can be seen getting up from a pew and talking to someone at the back of the church before pulling out a gun and opening fire.

Congregants can then be heard screaming and seen ducking under pews or running as papers fly to the floor.

Two people with minor injuries that were sustained while ducking for cover were treated at the scene, MedStar Mobile Healthcare spokeswoman Macara Trusty said.

Isabel Arreola told the Star-Telegram that she sat near the gunman and that she'd never seen him before Sunday's service.

She said he appeared to be wearing a disguise, perhaps a fake beard, and that he made her uncomfortable.

She said the man stood up, pulled a shotgun from his clothing, opened fire and was quickly shot by two congregants who were part of a volunteer security team.

"I was so surprised because I did not know that so many in the church were armed,” she said.

Tiffany Wallace told Dallas TV station KXAS that her father, Anton "Tony” Wallace, was one of the people killed.

She said her father was a deacon at the church and had just handed out communion when the gunman approached him.

"I ran toward my dad and the last thing I remember is him asking for oxygen and I was just holding him, telling him I loved him and that he was going to make it,” Wallace said.

Wallace said her father was rushed to a hospital but he did not survive.

"You just wonder why? How can someone so evil, the devil, step into the church and do this,” she said.

At a news conference Sunday night, Texas Republican Lieutenant Governor Dan Patrick said the gunman was killed within six seconds of opening fire.

Patrick hailed the state's gun laws, including a measure enacted this year that affirmed the right of licensed handgun holders to carry a weapon in places of worship, unless the facility bans them.

Patrick said the two congregants who drew their weapons saved "untold number of lives.”

Britt Farmer, senior minister of the church, said, "We lost two great men today, but it could have been a lot worse."

Officials have not released the names of the victims or the gunman.

FBI Special Agent in Charge Matthew DeSarno said they're working to identify the gunman's motive, adding that he is "relatively transient” but had roots in the area.

DeSarno also said the gunman had been arrested multiple times in the past but declined to give details.

Associated Press