The 17-year-old was shot during a suspected robbery involving marijuana, according to the Miami Herald, citing police. He later died in hospital.
His 15-year-old brother has been arrested in connection with the alleged attempted drug robbery that also left another 17-year-old dead.
Police allege the two brothers, armed with weapons, planned to rob the alleged drug dealer Monday afternoon and a shootout ensued. According to Florida law, an individual involved in a violent crime during which someone is killed can be charged with felony murder.
The 15-year-old was outside in a parked car when the shooting broke out, the Herald reported the police as saying.
Another 19-year-old man was wounded in the incident, police told the Herald.
"We heard like six straight shots," a male witness told NBC News."[We] came out here. Heard another four. Saw some guy come out with a gun. Some other guy behind him stumbling, he fell down and some chick came out screaming."
Foreign Affairs spokesman John Babcock said in an email statement the department is "aware of reports of a serious incident involving a Canadian family in Miami.
"Canadian officials are providing assistance to the family," Babcock said. "A full investigation is underway and we will continue assisting local authorities."
The Herald reported the teen brothers drove to an apartment in Coral Way neighbourhood of the city in a BMW with diplomatic plates.