The Houston Police Department was responding on Sunday afternoon to reports of a shooting at a Christian megachurch in Houston that is led by the televangelist and pastor Joel Osteen, it said on social media.

The details were unclear, but at least one person, a child, appeared to have been shot, Constable Alan Rosen of Harris County said on X.

The shooter is believed to have been shot by law enforcement, Sheriff Ed Gonzalez of Harris County said on social media. “We continue to assist in a methodical/thorough search of the complex,” Sheriff Gonzalez said.

Just before 3 p.m., the church, which is among the largest congregations in the United States and attended each Sunday by thousands of people, described the episode as “an active situation involving shots fired.”

Mr. Osteen, whose weekly televised services reach millions of viewers, could not be immediately reached on Sunday.

One eyewitness told the television station KHOU that she was inside the church when she heard several shots fired and saw a man who appeared to be in his 20s or 30s holding a pistol. She said she ran into a smaller room where she sheltered with about 10 other people, including a child.

“We were thankful,” the woman told KHOU. “It could have been worse.”

Governor Greg Abbott of Texas said in a statement on Sunday that he had offered state resources to assist the community and to “help bring swift justice to the criminal who committed this heinous act.”

This is a developing story.

Orlando Mayorquin contributed reporting.