A Texas sheriff said a gunman “was down” after a shooting at the Houston megachurch of celebrity pastor Joel Osteen on Sunday afternoon.

Harris County Sheriff Ed Gonzalez did not immediately provide more details in his post on X, the platform formerly known as Twitter.

Lakewood Church had earlier posted on social media there was an “active situation involving shots fired” at one of the largest megachurches in the USduring its typically busy Sunday services.

A news conference was scheduled for later by police and other law enforcement agencies. A heavy presence of police surrounded the Houston megachurch.

Worshippers could be seen leaving the building as authorities evacuated the church, and authorities said they were continuing to methodically search the building as a precaution.

Earlier, in a tweet on X, formerly known as Twitter, Lakewood Church said there was “an active situation involving shots fired” at the church.

“That is all the information we have at this time. Please pray for Lakewood and our community,” the church said in the post.

Jodi Silva, a Houston police spokeswoman, said officers were responding to the church but she did not have any additional details.

Christina Rodriguez, who was inside the church, told KTRK that she “started screaming, ‘there’s a shooter, there’s a shooter,’” and then she and others ran to the backside of a library inside the building, then stood in a stairway before they were told it was safe to leave.

People stood outside the building as authorities evacuated the church.

Officials later announced a reunification centre had been set up for people to find their loved ones, at a nearby fitness centre.

Witnesses told reporters that they heard multiple shots fired around the time the church’s 2pm Spanish language service was set to begin.

About 45,000 people attend weekly services at Lakewood, making it the third largest megachurch in the US, according to the Hartford Institute for Religion Research.

Mr Osteen’s televised sermons reach about 100 countries.