A little after 10 a.m. the babysitter, who is said to be a friend of the family, was on the phone with 911 asking for help.
When police and paramedics arrived they found the 9-month old boy struggling to breathe.
Officers closed off streets and rushed the baby to the hospital, but it was too late. He was declared dead in the emergency room.
An autopsy revealed the cause of death was blunt impact injuries with brain hemorrhage and contusions and lacerations of internal organs.
Police have questioned and later arrested the babysitter, 17-year-old Martin Quirindongo of Brooklyn.
He's charged with murder and manslaughter.