POLICE in New York say at least five people, including three infants, have been stabbed at an overnight day care centre in Queens.

NBC New York reports that authorities say the stabbings happened just before 4am (6pm AEST) on Friday.

One of the infants, a girl, is in serious condition, but none of the injuries is considered life-threatening.

Police say a 52-year-old daycare worker, identified as Yu Fen Wang, stabbed a female co-worker with a kitchen knife before stabbing three baby girls and injuring a dad of one of the babies.

One of the children was just three days old, another 20 days old and the third was just a month old.

It remains unclear how many stab wounds they each suffered and where on the body they were struck.

A sixth person, believed to be the attacker, was found in the basement of the day care centre in the Flushing neighbourhood.

Police say she had slashed her left wrist and is in custody at a hospital.

Police say a man who was injured was stabbed in the leg and is the father of a child who was at the day care centre.

A motive for the stabbings hasn’t been determined.

Eyewitnesses describe the bloody ordeal in emergency calls to 911.

“Help, help, help,” the person said. “Hurry up, because my baby’s already been stabbed twice. Someone came in and stabbed my baby twice.”

The dispatcher responded, “Someone stabbed her baby, she said?”

As crying is heard, the caller replied, “Yes. I don’t know this person … I don’t know where this person came from.”

A second person dialed 911 shortly after.

“I’m sleeping … and then I heard somebody yelling … and then they are killing people,” the person said. “I just saw the blood on the floor … and that somebody got hurt.”

The dispatcher asked if the assailant was still in the house.

“I don’t know. I don’t know. I cannot go out to check,” the caller replied. “I’m afraid.”

Police said a total of seven babies were found in the home, which sources said was being used as a citizenship mill.

“The daycare was illegal. They used it as a place for Chinese women to keep babies they gave birth to,” a high-ranking source said.