A woman was shot dead by two off-duty officers at Joel Osteen's Lakewood megachurch in Houston on Sunday. 

The woman, believed to be in her thirties, was accompanied by a child when she entered the church shortly before a Spanish-language service in the afternoon. 

She was dressed in a trench coat and carrying a long rifle when she opened fire. She was taken down by an off-duty police officer and an agent with the Texas Alcoholic Beverage Commission and died at the scene. 

Both officers have been placed on administrative leave while an investigation into the shooting is carried out.

Houston Police Chief Troy Finner said a five-year-old child was hit and is in critical condition in a local hospital. A 57-year-old man who was shot in the leg is also receiving hospital treatment. 

"I want to commend those officers. She had a long gun and it could have been a lot worse. But they stepped up and they did their job, and I want to thank them for that," said Finner.

In a statement, Osteen said he was "devastated" by the shooting and asked for prayers. 

"May the healing hands of God touch the lives of everyone involved and provide comfort during this difficult time. In the face of such darkness, we must hold onto our faith and remember evil will not prevail. God will guide us through the darkest of times," he said.

"Together, we will rise above this tragedy and stand firm in our commitment to love and support one another. 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. Please join me in continued prayer for healing and peace."

Texas Governor Greg Abbott said in a statement, "Our hearts are with those impacted by today's tragic shooting and the entire Lakewood Church community in Houston. Places of worship are sacred."