HOUSTON -- In her Houston hospital bed, LaPorsha Washington lay grieving and in shock over the death of her daughter.

"He left us a corpse. We no longer have a joyful 7 year old running around," she said.

Jazmine Barnes was shot and killed early Sunday when a stranger pulled alongside their car on a service road and opened fire on Washington and her four daughters. The 30-year-old mom was hit in the shoulder.

READ: Deputies looking for 4-door red pickup in fatal shooting of 7-year-old

Police believe the shooter, a white, bearded man in his 40s, was driving a red pickup truck. Security cameras caught a grainy image of the vehicle before the gunfire erupted.

"I replayed this moment in my head over a million times to see, did I cut this man off? Did I make a wrong turn in front of him?" Washington said. "I didn't — he fired at us for no reason."

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Washington was able to drive away. When she pulled over to call police, she realized Jazmine wasn't breathing. Her little second-grader died of a gunshot wound to the head.

Another daughter was hurt by the shattered window glass.

Now, Washington vows the killer will not go unpunished.

"Every crack, every rock, every corner that could be flipped, turn and turned around. We're going to be there," Washington said.

The sheriff is asking for the community's help to identify anyone who might fit the description of the shooter who also owns a red pickup. But that's a challenge in a city like Houston, where similar trucks are common. However, authorities are promising they will bring this individual to justice.

If you have information, call 713-221-6000 or Houston Crime Stoppers at 713-222-TIPS.

The family has set up a gofundme.com account to help pay for funeral and hospital expenses.