Commissioner Daniel Nigro says the deceased range in age from 5 to 15 years old. Nigro says a woman and teen who jumped from the second floor are hospitalized in critical condition.
Nigro says the woman is believed to be the mother of all eight children.
The fire broke out early Saturday at a single-family home in Midwood, a leafy section of Brooklyn known for its low crime and large Orthodox Jewish population.
Nigro says the hotplate was likely left on because of Sabbath prohibitions. Some very religious Jews refrain from doing work on the Sabbath, including turning on lights or appliances. As a result, some families may leave them on so they are usable without violating prohibitions against doing work.
There was no sign of working smoke detectors on the first or second floors, Nigro said, according to the New York Daily News.
"There is a smoke detector in the basement that was located but we did not see evidence on the first or second floor, Nigro said.
More than 100 firefighters battled the blaze and brought it under control at around 1:30 a.m, about an hour after it was reported.
Firefighters received a call at 12:23 a.m. about the blaze at a single-family home in Midwood, a leafy section of Brooklyn known for its low crime and large Orthodox Jewish population. Long said more than 100 firefighters responded and brought the blaze under control at around 1:30 a.m.
Long said the cause of the fire was being investigated by the city fire marshal's office.
Fire officials had no other immediate details, but the New York Post reported the blaze occurred in a brick home.
The newspaper said that as firefighters worked to put out the fire, paramedics struggled to help the victims.
Neighbor Nate Weber told the paper that he saw children being wheeled away on stretchers.
"I just turned away. I didn't even want to look," he said.
Weber told the New York Daily News he heard the children's mother yelling for someone to rescue her children after she jumped from a window.
"I heard a woman yelling: 'My kids are in there. Get them out! Get them out!'" he told the Post.