New York City police pressed forward today in investigating the deaths of four children and a woman who were stabbed at a Brooklyn residence, saying a person of interest had been taken into custody.

Officers arrived at the scene and found all five victims unconscious and unresponsive, police said. A one-year-old boy and two girls, aged seven and nine, were pronounced dead at the residence by emergency responders.

A boy, five, and the 37-year-old woman were taken to two Brooklyn hospitals where they were pronounced dead, police said.

Authorities were withholding the victims' names until family members had been properly notified.

Fire Department spokesman Jim Long said emergency workers responded just before 11pm on Saturday to a 911 call from a person stabbed at the residence in the Sunset Park neighbourhood.

Adjoining two-storey brick buildings sit on a tree-lined block in the working-class neighbourhood where the stabbings occurred.

A neighbour May Chan told the Daily News it was "heartbreaking" to learn of the deaths.

"I always see (the kids) running around here," Chan said. "They run around by my garage playing. They run up and down screaming."