Worshippers at celebrity pastor Joel Osteen's megachurch in Houston ran to find safety after Genesse Moreno, who was at the church with her seven-year-old son, began shooting an AR-15 style rifle earlier this month, police have said.

Two people were injured in the shooting - Moreno's seven-year-old son and a 57-year-old man.

In the video released by police, an off-duty officer is seen taking cover behind a corner as shots boom out on the audio.

"You killed my son!" shouts a female voice, believed to be Moreno.

More shots ring out.

"Stand down, I have a bomb. I have a f****** bomb."

In another clip, officers are seen requesting help for an injured boy who received a gunshot to the head.

"While we know there are unanswered questions, this is still an active investigation," Houston Police Chief Troy Finner said.

"We will continue to work with our local, state and federal law enforcement partners to thoroughly examine all aspects of this incident."

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Police say Moreno, 36, entered the church on 11 February between Sunday services with her son and opened fire.

She did not reach the main sanctuary and was killed after exchanging gunfire with two off-duty officers.

Police have told reporters that investigators were still trying to determine Moreno's motive and learn more about how she obtained the AR-style rifle she used.

Lakewood church is the third-largest in the US, with a maximum capacity of 16,000, and is regularly attended by 45,000 people every week, according to the Hartford Institute for Religion Research.

It has been led by Osteen, one of the wealthiest and most popular pastors and prosperity gospel preachers in the US, whose televised sermons reach about 100 countries, since 1999.

"In times like these, our faith is tested, but it is also strengthened. We don't always understand why things like this happen, but we know that God is in control," Osteen wrote on X.