The stabbings occurred just before 4am in the Flushing neighbourhood, of the Queens borough at what authorities described as a “short-term residential facility” where all of the victims and suspect lived.
Police said a 52-year-old woman allegedly stabbed a woman who works as a staffer in the facility eight times in the torso, then one of the babies’ fathers, as well as the three infants.
The adults and two of the infants are in stable condition at New York-Presbyterian Queens Hospital while the third baby is in serious but stable condition at Long Island Jewish Hospital.
According to NBC New York, one of the infants was just three days old and another born just a month ago.
Both girls were reportedly stabbed in the stomach.
Another baby, 20 months old, had lacerations on her ear, chin, and lip.
The man was stabbed in the leg and it is unclear whether his child is among the injured babies.
The suspect also had self-inflicted stab wounds to her wrist after police found her in the basement of the house.
She is in custody at the moment, but any possible motive for the stabbings has not been made public.
Police said they believe the suspect also worked there.
It has not been confirmed the home was actually licensed as a daycare facility.
“It looks to be an illegal” childcare facility, a police spokesman told AFP.
“We’re unsure of its legality at this time,” he added.
Four other children present in the daycare have been removed for observation.
One neighbour told CBS New York, residents nearby were woken up to screaming coming from the house.
“I got up, went and got dressed, and came out to see which house is it, because obviously I’m concerned, this is my neighbourhood,” they said.
NBC News reported police responded at approximately 3:30 am and shortly thereafter “officers accompanied by cops in white biohazard suits were seen carrying large bags to a specialised crime scene unit truck”.