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A search is underway for a white man suspected of what officials are calling an "unprovoked and senseless" shooting that killed a 7-year-old black girl while she was in a car with her mother and three sisters near Houston.

Jazmine Barnes was killed by a man driving a red pickup truck while she was riding in her mother's car Sunday morning on the way to a grocery store, authorities said.

Her mother, LaPorsha Washington, was also shot, and was hospitalized and released. Jazmine's 6-year-old sister was injured by shattered glass.

"To our public, we say this could be your family next because this person is out there somewhere," Harris County Sheriff Ed Gonzalez said during a press conference Monday. "This was unprovoked and senseless."

Sheriff's deputies have not released information on any possible motive.

Authorities said the suspect is a white man in his 40s with a beard. The sheriff said no person of interest has yet been identified, and he pleaded with the public for any information.

Gonzalez said at a briefing Wednesday that he is personally involved in the case, and that while investigators are aware of the concerns among some in the community that it might be race-related they are not ruling anything out.

“We don’t want to have tunnel vision and only focus on one particular motive. But we’re focused on a wide range of things right now,” Gonzalez said.

“Our top priority, for me personally and for our agency, is to bring justice for Jazmine,” Gonzalez said. “We’re not going to stop until we solve this case,” he said.

Jazmine Barnes, 7, was fatally shot in Harris County, Texas, on Dec. 30, 2018. Family photo

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Washington appealed to the public for help finding her daughter's murderer.

"I just want everybody to put in and step up and give any kind of information, anything for this man to be arrested because he took away an innocent child that did not deserve this, " Washington told NBC News on Monday. "She did not deserve this at all."

Washington, 30, said she had gone out with her four daughters to pick up coffee Sunday morning. She made a stop at a red light, and then heard gunfire. As bullets flew through the window, she tried to shield her older daughter who was sitting in the passenger seat, and was hit in the arm.

When the gunfire stopped, one of the girls sitting in the backseat said: "'Momma, Jazmine's not moving. She's not talking,'" Washington said. She said she turned around and saw Jazmine had been shot in the head.

Jazmine was confirmed dead on the scene, officials said.

Washington described Jazmine as "lovable."

"I wake up in the bed with Jazmine. Jazmine is going to be holding me, she's going to be kissing me. She loves the way you smell — she would smell you and say, 'Oh mommy, you smell so good,'" Washington said. "I can't imagine waking up without her every morning."

Washington believes the shooting was intentional, but said she did nothing to provoke it. She said after the driver shot into her car, he sped up to get in front of her and then slowed down to continue shooting.

She urged the shooter to turn himself in.

"You took away my child, and you took away my daughters' siblings," Washington said. "My baby comes and asks me, 'Where's my sister, is she coming back?'"

The sheriff said that investigators so far have not found anything to suggest the family knew the shooter. "So it still seems random in terms of their acquaintance," he said.

Gonzalez said that everything so far indicates a lone person was in the truck involved in the gunfire. "That’s what we need the public’s help on, is finding that individual," he said. He said "multiple shots were fired," but did not specify the type of gun used.

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives is assisting with the firearms evidence, and the Sheriff’s Office is also working with state and local partners, Gonzalez said.

Shaun King, a civil rights activist, announced Wednesday that a reward in the case was now up to $60,000 for anyone who could lead police to Jazmine's killer.

Christopher Cevilla, Jazmine’s father, told NBC News on Wednesday that his little girl was “an angel.”

"I just want them to just really know that my baby was an angel in disguise,” Cevilla said. “And God just saw fit for, to call her back home."

"It’s hard. It’s heartbreaking," Cevilla said. He said that the person who killed the child should come forward.

"One way or another, justice will be served," Cevilla said.