ANGLETON, Texas (AP) — A Texas mother who shot her four children over the weekend, killing two of them, faces murder charges, authorities said Sunday.

The 31-year-old mother is being charged with two counts of murder and two counts of aggravated assault with a deadly weapon, Brazoria County Sheriff Bo Stallman told reporters. She is being held on a $14 million bond.

Two of the children, ages 13 and 4, were fatally shot inside a vehicle Saturday. The other children, ages 8 and 9, are in “stable condition” after being flown by a medical helicopter to a Houston-area hospital, Stallman said.

The children’s mother called 911 to alert authorities after the shooting, Stallman said. Authorities recovered a weapon at the scene, he added.

“It is impossible to make sense of a senseless tragedy like this, but we will do everything we can to seek justice for these children,” Stallman said.

The mother is a resident of Montgomery County to the north of Houston, he said.

The shooting took place in Angleton, a city of about 19,500 and which serves as the county seat of Brazoria County. It is located about 45 miles (70 kilometers) south of Houston.