Two people were killed in a shooting at a church near Fort Worth, Texas, on Sunday morning and a third person has been taken to a hospital in critical condition, officials said.

MedStar Mobile Healthcare spokeswoman Macara Trusty told the Associated Press that two people were fatally shot at the West Freeway Church of Christ in White Settlement.

A third person in critical condition is being treated at a hospital and all of the victims are male, she said. MedStar is an ambulance service.

Authorities have not released any details about what led to the shooting.

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 added.

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 said she was told to direct inquiries to authorities.

WFAA, a Dallas-based TV station, reported that the church live-streamed the service on YouTube and that the video showed a man wearing a long coat produce a rifle or a shotgun which he fired twice before someone shot back.

Some members of the congregation ducked behind pews while others with handguns rushed the gunman, WFAA said. It said church members can be heard screaming and crying.

The AP hasn’t seen the video, which is marked as private on the video-sharing website.

Trusty said she was told by a supervisor at the scene that one of the people who died was the shooter.

White Settlement police have not responded to AP requests for comment. In an interview with Dallas TV station KTVT, Mike Drivdahl, the spokesman for the Fort Worth Fire Department, said he believes the gunman was among the three who were shot.

Two more people were treated for minor injuries at the scene, Trusty said.

White Settlement is about 8 miles west of Fort Worth.

Gov. Greg Abbott asked the state to pray for the victims, their loved ones and the White Settlement community.

“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, Texas, killing more than two dozen worshippers, before taking his own life.