The fire started in the kitchen of the seventh-floor apartment in the Butler Houses on Webster Avenue at around 1:20 p.m. Wednesday afternoon.
The babysitter, left in charge by her parents, may have been cooking and left the apartment briefly to get ingredients.
The children, girls ages 3, 4 and 7 and boys ages 8 and 10, were treated for smoke inhalation but were not seriously hurt.
They were released into the custody of their parents, who returned home after the fire.
The 15-year-old babysitter received a juvenile report for endangering the welfare of a child and was released into the custody of her guardian.
The cause of the fire is under investigation, but it appears to have been a stove fire.