The boy was being pushed in a stroller by his parents when four shots rang out around 7:20 p.m.
One of the shots hit Antiq Hennis in the left side of his head.
Witnesses said they heard the father screaming "My baby got shot! My baby got shot."
A local pastor drove the parents to the hospital where Hennis was declared dead.
"The family is distraught," said NYC community activist Bishop Willie Billops. "The young mother and young father are hurting badly."
A man was spotted running from the scene but no arrests have been made.
Commissioner Raymond Kelly says investigators believe the boy's father may have been the intended target. One Brooklyn resident said the boy's father may have been targeted following a dispute his brother had with the shooter.
A three-year-old was shot and seriously wounded as he slept in his family's Brooklyn apartment eight days ago. A babysitter was arrested in that case.
The Associated Press contributed to this report.