The victim, identified as Ralph Paul Yarl, 16, was shot twice and struck in the head by a white man Thursday evening, in Kansas City.
He was picking up his twin brothers from a friend’s house when he rang the wrong doorbell and was shot by the homeowner through a glass door.
Police said Yarl had been transferred to the hospital with injuries described as life-threatening, according to local media.
The case has now drawn nationwide attention and prompted outcry on Kansas City’s streets and online from celebrities and activists.
On Sunday, protesters gathered in front of the house where Yarl was shot, and demanded the homeowner face hate crime charges.
Two prominent civil rights attorneys, Lee Merritt and Ben Crump, who have agreed to take the case, criticized authorities in for releasing the gunman.
According to Kansas City Police Chief Stacey Graves, the homeowner had been released after 24 hours in custody, and that a statement from the victim would be needed before pursuing any charges.
The suspected shooter has not been identified by the authorities
"The information that we have now, it does not say that it's racially motivated, that's still an active investigation," Graves said.
"But as a chief of police, I do recognize the racial components of this case. I do recognize and understand the community's concern,” he added.
Graves said police were working "as expeditiously and as thoroughly as we can."
Police did not say how many times Yarl had been shot.
"Ralph is alive. He is healing," said his aunt, Faith Spoonmoore.
The incident has also sparked outrage on social media.
Mayor Quinton Lucas said there's a "thorough" investigation underway now. "My heart goes out to the victim of this shooting, the victim's family, my heart goes out to everyone impacted," he said.
Deadly shootings are a regular occurrence in the United States, a country of around 330 million people that is awash with an estimated 400 million guns.