Two were stabbed in their stomachs, and the 20-day-old was stabbed in her ear, lip and chin, according to the New York Police Department. Two knives were recovered at the scene and all the injured were taken to hospital in a critical but stable condition, police told reporters.
The babies range in age from 3 days to 1 month, NY police Assistant Chief Juanita Holmes told reporters Friday.
The 52-year-old suspect - an employee at the nursery - was taken into police custody and was being treated for her wounds and undergoing a psychiatric examination, authorities said.
Police said nine children and several parents were at the private home when the attack occurred.
No immediate charges were filed, and police said the motive was under investigation.
A female worker at the centre in Flushing, Queens was stabbed multiple times and a man thought to be a father of one of the children at the centre, was stabbed in the leg.
"There was one child with more serious injuries than the other two", NYPD Assistant Chief Juanita Holmes said at a news conference on Friday.
A police officer stands guard at the house were five people were stabbed overnight is seen in NY. Prosecutors said they were aged 13 days, 22 days and 33 days.
Of the children present during Friday's assault, five were girls and four were boys, she said. Police earlier described both adult victims as being in their 30s. Among the questions was whether the place was operating as an unlicensed childcare facility.