A man shot and killed his four children and the two adults who were looking after them, Texas authorities said late Wednesday.

A seventh person, a 15-year-old girl, was critically wounded and taken to a local hospital.

All of the children were either biological or adopted children of the suspect, said Sgt. Thomas Gilliland with the Harris County Sheriff’s Office.

Officials didn’t say what prompted the shootings. The man, identified as 34-year-old Ron Lee Haskell, is separated from his wife, who lives out of state, authorities said.

Officials: Prepared to take more lives

Haskell, is accused of killing two boys, ages 13 and 4, and two girls, ages 9 and 7. The adults who were fatally shot were a 39-year-old man and a 33-year-old woman. His relationship to the adults wasn’t immediately clear.

Authorities believe the suspect was prepared to take the lives of other relatives who lived nearby.

“Grandparents were also targets of him,” Gilliland said. “Fortunately, they were brought out of the house before that could happen, and we would have had more tragedy.”

Gilliland said the suspect faces multiple charges of capital murder.

Hours-long standoff

The suspect was taken into custody after a three-hour standoff that followed a short chase with sheriff’s deputies.

“The sheriff’s hostage negotiators have successfully resolved this,” said Harris County Constable Ron Hickman. “He’s removed from the vehicle without incident.”

During much of the standoff, the suspect held a gun to his head, while deputies surrounded him with their weapons drawn.

The shooting took place in Spring, about 20 miles north of Houston.