A man opened fire in a Houston home during a domestic dispute Wednesday night, killing four children and two adults, as well as critically injuring a teenage girl, police said.

The 15-year-old girl, who suffered a gunshot wound to the head, was able to call 911. She later told deputies the man was headed to her grandparents’ home and planned to kill them, the Associated Press reported.

Harris County Precinct 4 Constable Ron Hickman told The Washington Post that authorities were able to intercept the suspect en route. After a 25-minute pursuit, deputies cornered the man in a cul-de-sac a few miles from the scene. Authorities evacuated nearby homes and called in a hostage negotiator. Hickman said the suspect remained holed up inside a small Honda during the more than three-hour standoff with authorities.

Finally, the suspect emerged from the car, put up his hands and sank to his knees as deputies placed him under arrest. Sheriff’s Sgt. Thomas Gilliland told the AP the suspect was “cool as a cucumber.”

Gilliland said the suspected gunman is estranged from his wife, who lives out of state. Hickman said the two deceased adults were somehow related to the family.

“It appears this stems from a domestic issue with a breakup in the family from what our witness has told us,” Assistant Chief Deputy Constable Mark Herman told reporters.

When authorities arrived at the home in the northern Houston suburb of Spring at about 6 p.m. Central time, they found two adults and three children dead. Another child died later at a hospital.

The deceased children were two boys, ages 4 and 14, and two girls, ages 7 and 9. The two adults were a 39-year-old man and a 33-year-old woman, the AP reported.

Gilliland said the 15-year-old girl was in “very critical condition” at Memorial Hermann Hospital in Houston late Wednesday night.

A woman who said she lives across the street from the home described the family as “close-knit.”

“It was a Mormon family,” she told the Houston Chronicle. “They were very sweet and their kids were very shy. This is a sad, sad day.”

Authorities have not released the identities of the victims or the suspect.

Investigators plan to charge the suspect Thursday.

This story has been updated to reflect new information. The suspect was initially misidentified by authorities as the slain children’s father. Police did not explain the mistake.

Neighbors embrace each other following a shooting Wednesday in Spring, Tex. (Brett Coomer/Houston Chronicle via AP)