SEOUL (THE KOREA HERALD/ASIA NEWS NETWORK) - Seoul police on Tuesday (Dec 19) raided a local university hospital where four newborns died one after another in a span of less than 90 minutes, amid suspicion of medical malpractice.

Investigators from the Seoul Metropolitan Police Agency searched the premises of Ewha Womans University Medical Centre in Mokdong, western Seoul, to confiscate potential evidence, including incubators, injection tools and medical records, the agency said.

The move comes as the National Forensic Service (NFS) and health authorities are scrambling to figure out what caused the babies to die abruptly on Saturday evening.

Preliminary autopsies have found no evident reason for their deaths except abdominal bloating. Results from full autopsies will require up to a month, the NFS said.

On Monday, the Korean Centres for Disease Control and Prevention said at least three babies may had been infected with Citrobacter freundii, a bacterium that is common in adults but can cause respiratory, urinary and blood infections in infants.

The deceased were among 16 premature babies in the intensive care unit.

Three of the four were in the same row and the other was in the next row in a section of the same unit. Each row has three incubators and each section has two rows.

Police investigators also plan to summon six doctors and five nurses to check how the ICU was operated and whether they administered recommended dosages to the babies.

Forensic doctors on Monday raised the possibility of overdoses of IV fluid.

"While all four babies were under Total Parenteral Nutrition treatment, (receiving nutrition via injection) administering an overdose of IV can be detrimental, which often leads patients to death," said Yang Kyung Moo, chief of the forensic medical team at the NFS.

He said, however, that the cause can only be determined after the results of various postmortem tests are out.

The hospital has also separately formed an investigative unit comprising five medical experts, including Professor Kim Nam Joong, who studies infectious diseases at the Seoul National University.

Funerals were held for the four babies on Tuesday.