Part of a bridge in Seongnam, Gyeonggi Province, collapsed, killing one pedestrian and leaving another in critical condition, authorities said Wednesday.

A part supporting the sidewalk of Jeongjagyo gave way at around 9:45 a.m Wednesday. The two, strangers to each other, were reportedly on the bridge at the time. Both fell into the stream below, about 5 meters below the bridge, according to reports.

A woman in her 30s was taken to a hospital with cardiac arrest, but was later pronounced dead, while a man in his 30s was transferred to a hospital nearby. He is reportedly in critical condition.

Police are investigating the exact cause of the incident. Local reports say the bridge collapsed as a water pipe underneath was damaged due to heavy rain that fell overnight. Police plan to investigate various possibilities, including a burst pipe and corrosion of rebars.

Police checked security footage and found that the bridge suddenly crumbled, rather than collapsing slowly. “It seems like a sudden accident. It collapsed instantly,” a police official said.

According to the relevant laws, local governments are required to conduct safety inspections of bridges once a year and to conduct detailed checks every two years. The police plan to look into related records of safety inspections conducted by the Bundang-gu Office.

Seongnam City Deputy Mayor Lee Jin-chan visited the scene of the accident and said, "As a public official in charge of managing the city, I am very sorry. The officials will do our best to honor the deceased and care for the injured."

Built in 1993, Jeongjagyo has walkways on both sides of the road. The 110-meter bridge has six lanes of traffic.