A 52-year-old babysitter in “psychological distress” stabbed five people—including three babies under her care—at a New York maternity center that appears to be part of a birth-tourism facility for foreign mothers who want to deliver their children in the United States, authorities said.

Two senior law enforcement officials told The Daily Beast that the Friday morning incident in the borough of Queens happened at Mei Xin Care Inc. in a building that may be a so-called maternity hotel for Chinese women who want their babies to get automatic American citizenship.

The alleged assailant, identified by a senior NYPD official as Yu Fen Wang, was found in the basement of the three-story building with what appeared to be a self-inflicted slash to her left wrist, authorities said. Charges are pending.

The Queens District Attorney's office said Yu was being held at a nearby hospital Friday where she was undergoing psychiatric evaluation and being treated for her wounds.

A cleaver was on a kitchen counter near Yu, the official said. A second weapon—a bloody kitchen knife—was recovered in the first-floor bathroom, where the stabbing took place.

All of the victims—babies from 13 days old to one month old and an adult man and woman—are in stable condition at nearby hospitals, authorities said.

One baby girl was “more seriously injured than the other two” and at one point doctors thought she would die, but she has since been upgraded to critical but stable condition, said NYPD Assistant Chief Juanita Holmes during a press conference.

Holmes said police are investigating what takes place in the facility at that hour and how it is being used. The state and city agencies that oversee daycares have each launched investigations into the facility as a possible illegal operation.

Birth tourism is a growing phenomenon in the United States. As The Daily Beast has reported, Russians have flocked to Trump properties in Miami, paying up to $75,000 for luxury lodging and medical care. And Chinese moms-to-be favor “maternity hotels” on the West Coast. There is nothing illegal about it unless they lie on their visa applications or commit health insurance fraud.

A preliminary investigation determined that the stabbing spree began with an attack on a 63-year-old woman who works at the facility, authorities said. The 31-year-old man, the father of a child at the daycare, was injured when he intervened and was stabbed in the leg. The attack on the children took place after.

Recordings of the two 911 calls made to police around 3:45 a.m., obtained by NBC New York, capture the horror that unfolded in the middle of the night. In one call, a woman can be heard telling the dispatcher: “Help, help, help. Hurry up, because my baby's already been stabbed twice. Someone came in and stabbed my baby twice.” In the second, a caller tells the dispatcher, “I'm sleeping, and then I heard somebody yelling. They are killing people. I just saw the blood on the floor.”

Officers arrived to find the three infants with stab wounds to the abdomen, Holmes said.

Officers also found the man and woman who directed police to the basement, where Wang had fled and locked the door, authorities said.

Wang was found unconscious, but officers applied a tourniquet, at which point she regained consciousness, was arrested and taken to a hospital, Holmes said. The injuries to the two other adults are not considered life threatening.

The childcare facility is located on the ground floor of the building which has apartments on the upper floors, authorities said. Police found nine babies—five girls and four boys— and 11 cribs in the building, authorities said. Parents of some of the children were in the building.

Holmes said that the only previous complaint to the building that police have found in their records is a 311 call in 2011 for children screaming.