59-year old Anthony Byrd faces multiple charges, including criminally negligent homicide, assault, and reckless endangerment.
The incident happened at the intersection of Dekalb Avenue and Clermont Avenue in Fort Greene just before 12:50 p.m.
Authorities say Byrd was making a turn onto a Brooklyn street just before 1 p.m. Saturday when he attempted to avoid two pedestrians in the crosswalk and hit a car. Police said he continued to hit other cars and some pedestrians.
The child was pinned and pronounced dead at the scene.
The boy's mother was among at least three others who were injured.
The FDNY says it transported four people to Kings County Hospital, including the child's 47-year-old mother and 5-year-old brother. An 18-year-old woman not believed related to the other victims was also hurt, as well as the driver of the other vehicle.
Their injuries were not believed to be life threatening.