Infant in NICU
Infant in NICUiStock

A nurse in Ulm, Germany, has been arrested on suspicion of trying to poison five premature babies with morphine.

Doctors at the Ulm University hospital began investigating the issue late in December, when "five infants, aged between one day and one month, suffered shortness of breath almost simultaneously," Ulm Police Chief Bernhard Weber said Thursday at a press conference.

"Only because of immediate action taken by the staff could the five lives be saved," he added.

Hospital staff initially believed the babies had contracted an infection, but nine tests came back negative.

All of the infants, who were between one day and five weeks old, survived, and none are expected to suffer long-term damage.

Though at least two of the newborns had not been prescribed morphine, investigators found traces of the painkiller in the urine of all five of the affected infants.

An inspection of the nurses' lockers led to the discovery of a syringe containing morphine-infused breastmilk.

According to The Guardian, the university hospital notified police of the incident on January 17.

The nurse in question has been described as a "young" woman and was taken into custody on Wednesday. Prosecutors believe her actions were premeditated.

If charged, the woman would face multiple counts of causing grievous bodily harm and attempted manslaughter. Meanwhile, she has denied the charges.

In a statement, the hospital said: "We very much regret that this incident could have happened and we sincerely apologize to the parents and children." It added that "rapid medical intervention" ensured that the babies "were stable again within 48 hours and they could breath on their own again."