(CNN) The father of a 7-year-old girl killed in a drive-by shooting pleaded with the public to help authorities in the manhunt for a gunman who opened fire on a mother and children in a car near a Houston-area Walmart.
"I just want anybody, whoever, out there that knows anything about the murder of my daughter, to just please step up as if it was your own," an emotional Christopher Cevilla told reporters on Monday. "Just put yourself in my shoes, in my family's shoes."
Jazmine Barnes, her mother and three siblings were driving near the store in northeastern Harris County close to 7 a.m. on Sunday when a man pulled next to them in a red or maroon four-door pickup truck and fired several shots, the Harris County Sheriff's Office said. Jazmine was killed at the scene, Sheriff Ed Gonzalez said.
Jazmine's mother, LaPorsha Washington, 30, was shot in the arm and Jazmine's 6-year-old sister was struck by shattered glass, the sheriff said. Two teens were unharmed.
Authorities were working to determine whether the shooting was random or targeted, and they are searching for the shooter. He is described as a bearded white male, possibly in his 40s, who was wearing a red hoodie, according to the sheriff's office. The victims are black.
"It's our belief that it was totally unprovoked, whatever it was, and we're leaving no stone unturned. We're going to leave every motive out there as a possibility," Gonzalez said.
He added: "There was nothing to indicate that the family did anything wrong in any way. They were simply just driving along the service road when this happened to them."
Washington told CNN affiliate KTRK she turned around and looked back at the street and heard shots.
"They came through my window, broke my glass, and hit me in my arm," she told the station from her hospital bed.
Washington said: "He sped off in front of us and stopped, and still continued to fire at us."
"It was not fair. He intentionally killed my child for no reason. He didn't even know her. He didn't even know who she was," she said.
Washington said one of her daughters discovered Jazmine had been shot.
"She said, 'Momma, Jazmine's not moving. She's not talking.' I turned around and my 7-year-old was shot in the head," Washington said, according to KTRK.
The sheriff said authorities don't have information that the gunman yelled anything to the victims during the shooting.
"We don't have any reason to believe he wasn't aware of what he was doing," the sheriff said.
The sheriff's office released a photo of the pickup truck believed to be involved in the shooting taken from a surveillance video taken before the incident. Authorities also urged the public to look at their surveillance footage and try to remember if they had seen the truck before.
"Please keep this family in your prayers," Gonzalez said in a Facebook post. "A total of 5 occupants in the car witnessed this child, their loved one, shot and killed before their eyes. So senseless. It's never easy, and extra hard during the holiday season."
The sheriff said he had never met the 7-year-old but noticed her "million-dollar smile" in photographs.
Cevilla said his daughter was "loving, caring, very passionate with people, very sweet, just a innocent young girl, very smart in school."
He added: "It's just a lot of things that's been robbed of me and my family at this moment that we will never be able to get back."
The Sheldon Independent School District said Jazmine was a second-grader at Monahan Elementary and "will truly be missed by all students and staff."
Gonzalez urged the suspect to turn himself in.
"My hope is that every passing moment that his conscience is eating away at him ... and I hope it's that case forever," he said.
The sheriff said: "We're going to find you."