All of those wounded in the attack, which happened before 4 a.m., were hospitalized but expected to survive. The 52-year-old suspect was in police custody.
No immediate charges were filed, and police said the motive was under investigation.
Investigators were trying to piece together what happened inside the building, a three-story, multifamily townhouse in a neighborhood popular with Chinese immigrants in the Flushing section of Queens. Among the questions was whether the place was operating as an unlicensed child-care facility.
Police responding to a 911 call discovered 3-day-old girl and a 1-month-old girl who had been stabbed in the abdomen, and a 20-day-old girl with cuts to her ear, chin and lip. The father of one of the children and a woman who worked there were also stabbed, police said.
A butcher knife and meat cleaver were found at the scene.
The woman suspected in the attack was discovered bleeding and unconscious in the basement, and after officers applied a tourniquet, she regained consciousness and was taken to the hospital, police said.
State records indicate that a business called Mei Xin Care Inc. was registered at the address, but there was no listed phone number for that company.