Investigators believe Devonte Lockett shot Tristian Hutchins and his 5-year-old sister outside a Third Ward shopping center on March 1.
Tristian died last week.
He was shot in the head as his mother ran inside a Third Ward salon. His 5-year-old sister was shot in the leg.
A third sibling was not injured in the shooting.
Devonte Lockett arrested in death of 8-year-old boy
At a press conference Friday, Houston Police Chief Art Acevedo, Mayor Sylvester Turner and Congresswoman Sheila Jackson Lee discussed Lockett's arrest.
"We've had a lot of tips coming in," Acevedo said.
He added that the department is looking for possibly other suspects in the fatal drive-by shooting.
Turner also pledged an additional $1 million for HPD.
"I have authorized an additional $1 million in police overtime to work in communities to solve this and other crimes and build relationships with diverse neighborhoods," Turner said.
TIMELINE: Children killed by gun violence in Houston
Lockett is no stranger to police.
According to documents, he was previously charged for evading arrest, possession of a controlled substance, and for carrying a handgun in a motor vehicle.
Hutchins was the 10th child shot and killed in Houston in the past year, police say.
News of the child's murder sent shockwaves through the community, with Turner and Acevedo weighing in on the crime.
Mayor Turner tweeted after hearing the news of Lockett's arrest, saying, "Violence against our kids will not be tolerated. We will work overtime and spend whatever it takes to protect our children."
Young kids injured in driveby shooting while sitting in mom's car outside nail salon
Boy and girl shot in drive-by shooting outside nail salon
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