Three medical professionals accused of medical negligence that authorities believe was responsible for the deaths of four newborns at a hospital in Seoul were arrested early Wednesday morning.

In December, four premature babies at Ewha Womans University Medical Center’s neonatal intensive care unit died one after another in a span of less than 90 minutes.

Dr. Cho Su-jin, a pediatrician who also serves as a professor at Ewha Womans University College of Medicine, was arrested along with another doctor and a head nurse.

According to an investigation by the Health Ministry and the National Forensic Service, the newborns died of sepsis caused by Citrobacter freundii infection. They concluded that the newborns were infected with the bacterium, which can cause urinary, respiratory and blood infections in infants, through contaminated injections.

The injections are known to be lipid-based nutritional supplements.

Investigators believe that one of the nurses violated sanitary regulations while preparing the lipid-based supplements for injection. Doctors, including Cho, are accused of neglecting their duties, including overseeing infection control measures in the hospital’s neonatal intensive care unit.

A number of representative bodies of medical doctors, including the Korean Association of Obstetricians & gynecologists, issued statements protesting the prosecution’s decision to arrest the three medical professionals. Some 32,000 doctors also signed a petition asking for an investigation without detention.

By Claire Lee (dyc@heraldcorp.com )