Trigger warning: child death

Last month, three babies died after contracting a waterborne bacterial infection at the Geisinger Medical Center in Danville, Pennsylvania. After a month-long investigation, the hospital said Friday that it had finally found that the cause of these deaths was breast milk that had been contaminated by hospital equipment.

The breast milk made eight babies sick and resulted in the death of three in a neonatal intensive care unit, Geisinger Medical Center said. Infection control specialists say that the equipment used to measure and dispense donor breast milk was tainted with Pseudomonas bacterium, a hospital spokesperson confirmed to CBS News. Hospital officials insist that the milk itself was not the source of the bacteria. Following the discovery, the hospital says it has switched to employing only single-use equipment.

"We have had no new cases of infants becoming ill from Pseudomonas in the NICU since making this change," Dr. Edward Hartle, Geisinger's executive vice president and chief medical officer, said in a statement.

The hospital said some preemies and expectant mothers are being diverted to other facilities while it works with state health officials to normalize operations.

"We would like to extend our sincere apologies to the families who have been affected by this incident. We know that the public holds us to the highest standards, and we will continue to strive to live up to those expectations as we have throughout our history, constantly improving on what we do and how we do it," Hartle said.

The bacteria are common and often innocuous but can result in illness in "very fragile patients," Dr. Frank Maffei, the hospital's chair of pediatrics, said at a news conference when the incident was first reported. The deaths, he said, "may have been a result of the infection complicating an already vulnerable state."

The parents of one of the preemies who died filed a lawsuit against the hospital last month for its alleged negligence in protecting their son from the lethal infection, which had already resulted in the death of two other babies. "A key aspect is to determine whether this was an ongoing problem there. We now have additional work to determine whether these infection control procedures were deficient for a period of time longer than Geisinger's statement suggests," the family's attorney, Matt Casey, told The Associated Press.

RELATED: NICU Announces A Cleanslate Machine That Kills Bacteria On Cellphones

Casey, who also represents the family of the second baby who died from the lethal infection, said his investigation has shown earlier Pseudomonas infections in the Geisinger NICU in which at least one baby died. But he added that he does not yet know if those earlier infections were linked to the hospital’s breast milk equipment. “A key aspect is to determine whether this was an ongoing problem there. We now have additional work to determine whether these infection control procedures were deficient for a period of time longer than Geisinger’s statement suggests,” he said.

A hospital spokesperson declined to comment on Casey's statement about the earlier infections, citing the pending lawsuit.