A 20-year-old man in Texas was arrested Saturday and charged in the death of 7-year-old Jazmine Barnes, who was shot and killed while riding in a car with her family in Houston. Another man is being held in connection with the shooting but has not yet been charged, a lawyer for the girl's family said.

Eric Black Jr., 20, was charged with capital murder and appeared in court early Sunday morning, wearing handcuffs and an orange jumpsuit. He was ordered held without bail. A prosecutor said Black admitted to driving the car when his passenger opened fire.

Lee Merritt, an attorney for the Barnes family, told CBS News another suspect had also been arrested.

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Authorities said they believe the suspects thought the car belonged to someone else and Jazmine's death was a case of mistaken identity.

"The intended targets were likely someone else, but instead they fired upon LaPorsha, Jazmine and her siblings in this case," Harris County Sheriff Ed Gonzalez said at a news conference Sunday. LaPorsha Washington is Jazmine's mother.

The shooting occured Dec. 30 in Houston when a car pulled alongside the vehicle carrying Barnes and her family at a stoplight and a gunman opened fire. Jazmine died of a gunshot wound to the head, and her mother was hit in the arm.

In the days following the shooting, Washington said she believed it was racially motivated. Her 15-year-old daughter, who was also in the car, initially said the shooter was a white man in a red truck, and police released an artist's sketch Thursday showing a thin, white man with a 5 o'clock shadow. Black, the alleged driver, is African American. The full name of the alleged gunman is not yet known, but Harris County Sheriff Ed Gonzalez said Sunday the individual is also African American.

In the press conference Sunday, Gonzalez said there was indeed a red truck at the stoplight when shots rang out, but said investigators now believe the person or people in the truck were nothing more than witnesses. He urged the unidentified driver of the truck to come forward.

Gonzalez said investigators don't believe "in any way" that family members were involved in anything "nefarious." He added that investigators believe two people were involved in the shooting, but would not comment further since Black is the only individual who has been charged.

"We feel that they were truthful. This just went down very quickly when the gunfire erupted," Gonzalez said. "You're talking about small children — they witnessed something very traumatic. And it is possible that the last thing they did see was indeed that red truck and that driver that was in that truck, and that's what they remembered last."

Jazmine Barnes Harris County Sheriff's Office

Earlier Sunday, a prosecutor presented details of the case against Black at a hearing at Probable Cause Court in downtown Houston. Appearing by video conference, the prosecutor said Gonzalez had received an anonymous tip passed along by journalist and activist Shaun King. The source implicated two men identified as "LW" and "EB" in the shooting after authorities asked the public for help identifying the assailants.

The source for the tip said the suspects thought the vehicle carrying Jazmine was another vehicle they had seen earlier in the day, the prosecutor said, and didn't realize they had hit the wrong vehicle until seeing the news later that day.

The source provided the sheriff with the name of an Instagram account used by one of the suspects, which investigators determined belonged to Black, the prosecutor said.

On Saturday, police stopped Black in a grey Kia for failing to signal when changing lanes, and held him for suspected marijuana possession after a deputy said he saw a plastic bag with what appeared to be marijuana in his glove box when Black opened it to find his insurance card. The officer searched Black's car, found more marijuana and detained him, the prosecutor said.

Eric Black Jr. appears in court for a probable cause hearing Sunday, Jan. 6, 2019. OnScene.TV

Homicide detectives interviewed Black on Saturday, and the prosecutor said Black admitted to driving the vehicle involved in the shooting. Black told investigators "LW" — identified in court only as "Larry" — was seated in the front passenger seat of a rental car and fired at the vehicle carrying Jazmine. Black returned that rental car after the shooting and picked up the car he was driving when he was pulled over Saturday.

The prosecutor said in Sunday's hearing that Black then agreed to a search of his residence, where police found a 9 mm pistol consistent with shell casings found at the site of the shooting.

Gonzalez, the sheriff, said Sunday that police had received more than 1,000 tips in the case. A reward of $100,000 had been offered for information leading to an arrest. At a rally in Houston on Saturday, more than 500 people honored Jazmine and helped raise money for the family.

Zachary Hudak and Alexis Bravo contributed reporting.