HOUSTON — Relatives of Jazmine Barnes, the 7-year-old Texas girl who was fatally shot inside a moving car, grieved on Saturday at an emotionally charged rally not far from where the gunman opened fire on a family that was out on a morning coffee run.

Nearly 1,000 people gathered to honor Jazmine and to urge law enforcement to find the man who the police said attacked on Dec. 30 without provocation.

Jazmine, who was black, was in the car with her mother and three sisters when a white man pulled his red pickup truck beside them and began shooting, the police said. A bullet struck Jazmine in the head and she died at the scene, the police said. The gunman was described as a man in his 30s or 40s wearing a hooded sweatshirt.

“We’re going to find him no matter what corner we have to turn,” said LaPorsha Washington, Jazmine’s mother, who was driving at the time of the attack. “We’re going to find you.”