Emergency responders were called to the boy's home after he shot himself at about 4:15 p.m. Sunday, The Detroit News reported.
"Responders tried very hard to save the boy but were unable to," Redmond said. "He was transported to St. Joseph Hospital in Ann Arbor and was declared dead at 5 p.m."
Police arrested a 30-year-old man who was a live-in friend of the boy's father on suspicion of manslaughter with gross negligence, the Detroit Free Press reported.
The man, whose name was not reported, is expected to be formally charged, police said.