A seven-year-old girl died Sunday after a man in a pickup truck sprayed bullets into a vehicle parked in a Houston-area Walmart.
Harris County Sheriff Ed Gonzalez identified the girl as Jazmine Barnes.
Washington said one of her daughters discovered Jazmine had been shot.
The girl, whom police have not yet publicly named, was killed around 7am on Sunday in a vehicle alongside her mother and three sisters as the auto exited the Walmart on Wallisville Road in northeast Houston.
Authorities were working to determine whether the shooting was random or targeted.
The suspect is described as a white man in his 40s and has a beard.
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"You should have a heart and step forward and say you did this to this baby because she did not deserve what you did to her".
The sheriff said authorities don't have information that the gunman yelled anything to the victims during the shooting. Authorities are asking the public for tips and appealing to nearby residents and businesses to review surveillance video for the red pickup truck.
"Please keep this family in your prayers", Gonzalez said in a Facebook post. "So senseless. It's never easy, and extra hard during the holiday season".
Another girl aged about ten was non-seriously injured by flying glass.
The Sheldon Independent School District said Jazmine was a second-grader at Monahan Elementary and "will truly be missed by all students and staff".
He urged the suspect to surrender.
"I hope with each passing moment his conscience is eating away at him", Gonzalez said, later adding, "Do the right thing and turn yourself in".
'Because we will be looking for you.