Shawntaze "Cameron" Moore was inside a home in the 15700 block of Ward near Puritan and Schaefer when he was shot around 10:30 p.m. Saturday. Another child was also in the home at the time.
Investigators say they don't know if Moore or someone else pulled the trigger, but they do believe someone who shouldn't have access to the gun got ahold of the weapon.
"How many times this summer have we talked about babies losing their lives because adults have put guns in their view?" Detroit Police Chief James White said.
White also said the gun used is not legally owned.
"The gun's not legal at all, we do know that," he said.
An adult is in custody in connection with the incident, and a report is being submitted to the prosecutor's office.
Meanwhile, Moore's family is planning to hold a vigil for the boy Tuesday night.