Six people were killed in a shooting Wednesday after a gunman opened fire in a home in suburban Houston.

Prosecutors said the victims include four children and two adults, all of whom had been tied up and shot in the back of the head.

The gunman, 33-year-old Ronald Lee Haskell, surrendered after a car chase and a four-hour standoff with police. He was booked Thursday on charges of murder.

Investigators said Haskell, wearing a FedEx uniform, arrived at the home in Spring, a suburb of Houston, Texas. Once inside, the man gathered the children and waited for their parents to arrive home. He then proceeded to shoot the seven people inside the home.

Two adults and three children were found dead inside the home, while another child died while being airlifted to a hospital, according to the Harris County Sheriff's Office.

Deputy Thomas Gilliland said among the fatalities were a 39-year-old man, a 33-year-old woman, two boys aged 4 and 14, and two girls aged 7 and 9.

A 15-year-old girl suffered a bullet fracture to her skull, but she survived the shooting by playing dead. She was taken to Memorial Hermann Hospital, where she remains in critical condition.

The teen told authorities that the shooter also planned to target her grandparents.

"It appears this stems from a domestic issue with a breakup in the family from what our witness has told us," Mark Herman, assistant chief deputy constable of the Harry County Precinct 4 Constable's Office, said.

Authorities said Haskell was "married to a relative of the residents of this home."

FedEx released a statement on Thursday, saying that Haskell had "provided service for FedEx, but has not done so since January."

Residents, meanwhile, were left shocked by the tragic shooting.

Wesley Carr, who lives in a nearby subdivision, said the Spring neighborhood is a typically quiet residential area.

"I've lived here 20 years. It's a very quiet neighborhood. It's not a through area," Carr told the Houston Chronicle. "People just don't come here."