Texas Boy, 4, runs over 16-month-old sister

A Westminster, Texas, family is "hurting" after their 4-year-old son managed to set the family's pickup truck in motion, rolling over and killing his 16-month-old sister, their pastor said.

The family was loading up their pickup before heading to a relative's house on Sunday at 1 p.m. when the 4-year-old grabbed the keys to the truck, climbed inside and started the engine, according to a statement from the Collin County Sheriff's Office.

The boy then shifted the truck into neutral, causing the vehicle to roll forward, the sheriff's office said. The children's father heard the car start and ran outside to investigate, but he was too late.

The vehicle struck the little girl then rolled into their neighbor's fence, according to the sheriff's office. She died instantly from the impact. The name of the family wasn't provided by police.

Tom Ogden, pastor of the church the family attends in McKinney, Texas, drove to the family's home after getting news of the accident. Ogden, who has known the family for 15 years, had been with them in church about one hour before the accident.

"I told them for a fact this wasn't an act of God or an act of the devil, it was pure and simply an accident that happened," he said. "For the weeks and months to come, it's going to be a long healing process."

Ogden said the boy understands what happened on Sunday, and that he would be going into counseling. "He's got a healing process in front of him also. He's going to miss his little sister," he said.

Ogden said the whole family was banding together to deal with loss of their youngest member.

"When something happens to one of them, it happens to all of them, because they are a very, very close-knit family," he said. "She was the baby."

"The dad and the brother, they still can't understand how that can happen so quickly," Juan Verde, the victim's uncle, told ABC Dallas affiliate WFAA-TV. "We don't have too many tragedies in our family, and this is one of them."

The Collin County Sheriff's Office said the investigation into the accident is ongoing.