Two children were killed and two more were critically injured in a shooting early on Saturday near the Houston suburb of Angleton, Texas, authorities said.

The Brazoria county sheriff’s office said in a Facebook post that deputies responded to reports of the shooting and found two children, ages 13 and four, fatally shot. Two other children, aged eight and nine, were flown by medical helicopter to a hospital and were in critical condition.

“Fortunately, the two injured children are now in stable condition,” Madison Polston, the sheriff’s public affairs officer, said in an email Saturday.

A woman has been arrested in connection with the shooting, Polston said. Investigators were working to verify how the woman and children are related.

“There is no ongoing threat to the community,” the Facebook post said. Officials offered no other details about where the shooting took place or the circumstances that led up to it.

Phone and email messages left for several spokespersons for the county were not immediately returned.

“While details are still developing, the loss of two children in such a manner is a tragedy,” the sheriff’s office wrote in the post. “Our thoughts are with the family and everyone affected as we continue to learn more about this heartbreaking situation.”

Angleton is a city of about 19,500 and is the seat of Brazoria county. It is located about 45 miles (72km) south of Houston and is within the Houston–The Woodlands–Sugar Land metropolitan area.