A man pulled out a shotgun at a Texas church service and fired on worshippers Sunday, killing two people before he was shot to death by congregants who fired back, police said.

Authorities at a Sunday evening news conference praised the two congregants who opened fire as part of a volunteer security team at West Freeway Church of Christ in White Settlement. It was unclear if the two people who were killed were the two who shot at the gunman.

“This team responded quickly and within six seconds, the shooting was over. Two of the parishioners who were volunteers of the security force drew their weapons and took out the killer immediately, saving untold number of lives,' said Lt. Gov. Dan Patrick, who also hailed the state's gun laws.

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

Authorities said there were more than 240 parishioners in the West Freeway Church at the time of the shooting.

White Settlement Police Department Chief J.P. Bevering said the gunman had sat down in a pew before getting up, taking out a shotgun and firing at a parishioner, who was killed. He said the church's security team then “eliminated the threat.”

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.

An elder at the church told the New York Times that one of those killed was a security guard who responded to the shooter, calling him a dear friend.

“He was trying to do what he needed to do to protect the rest of us,” said the elder, Mike Tinius.

“It’s extremely upsetting to see anyone committing violence,” he said.

Tinius said he didn't know the gunman and that the shooting appeared to be random.

A woman who answered the phone at the West Freeway Church of Christ told the AP she could not answer any questions and that she was told to direct inquiries to authorities.

An elderly couple walks from West Freeway Church of Christ hours after a fatal shooting at the church, Sunday, Dec. 29, 2019, in White Settlement, Texas. AP

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. Parishioners 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.

Gov. Greg Abbott asked the state to pray for the victims, their loved ones and the community of White Settlement, about 8 miles (12 kilometers) west of Fort Worth.

“Places of worship are meant to be sacred, and I am grateful for the church members who acted quickly to take down the shooter and help prevent further loss of life,” Abbott said in a tweeted statement.

It is not the first deadly shooting to take place at a church in Texas. In November 2017, Devin Patrick Kelley opened fire on the congregation at a church in Sutherland Springs, killing more than two dozen worshippers, before taking his own life. And in 1999, a gunman killed seven people in Wedgwood Baptist Church in Fort Worth before detonating an explosive device and killing himself.

Sunday's shooting in Texas was also the second attack on a religious gathering in the U.S. in less than 24 hours. On Saturday night, a man stabbed five people as they celebrated Hanukkah in an Orthodox Jewish community north of New York City.