The suspect, Tyrese Simmons, 19, turned himself in on Thursday and faces a murder charge, Dallas Police said in a statement.
Simmons allegedly went to an apartment complex to confront a rival rapper after two exchangeable disparaging comments, according to authorities. The other person did not come out of his apartment, so Simmons circled around the back, police said.
Then Simmons opened fire, shooting at the wrong apartment and fatally wounding Brandonia, police said.
"As adults, as parents as police officers, we are supposed to make them safe, as community leaders, we're supposed to make them safe," said Dallas Police Department Maj. Danny Williams told the affiliate. "She was sitting in every house, she felt safe … she was only 9 years old."
Simmons' bail was set at $ 500,000. Information on his attorney was not immediately available.