Police said Friday they have been questioning officials over Thursday's partial collapse of a bridge in Seongnam, Gyeonggi Province, that killed one person and heavily injured another to look into possible irregularities in the recent maintenance and safety inspections of the structure.

At around 9:50 a.m. on Thursday, the pedestrian section of the bridge Jeongjagyo near Jeongja Station in Jeonga-dong, Bundang-gu, partially collapsed due to a yet unspecified cause. The accident killed a 39-year-old woman and inflicted severe injuries on a man in his 30s.

Investigators of the Gyeonggi Nambu Provincial Police Agency on Thursday summoned officials from the Bundang-gu Office who are in charge of bridge management. They were questioned about the routine inspection of Bundang-gu bridges that took place from Aug. 29 to Nov. 26, 2022, in which Jeongjagyo got a B rating -- the second highest of five grades -- for safety.

The bridge in question got a C rating in 2021. It underwent restoration works beginning in 2020 to get its safety rating upgraded to B last year. This included a four-month repair in 2020 by the Bundang-gu Office with a price tag of 384 million won ($290,400).

According to the related law, a B rating refers to a "satisfactory" state, which means there are minor defects that do not affect it functioning as a structure but require partial repairs to improve durability.

Police declined to comment on the specifics of the investigation, but it has been reported they are also looking into bridge maintenance that took place last year. They are planning to call in other officials related to the safety inspection and repair of the bridge for questioning.

It is now unclear what exactly caused the structural failure of the 30-year-old bridge -- 108 meters long and 26 meters wide -- that made it collapse. Problems with the structural integrity of the bridge itself is but one possibility, with some speculating about a collapse of the surface layer in the area being caused by heavy rain.

The city of Seongnam has closed off Jeongjagyo, along with Buljeonggyo, also in Jeongja-dong, and Sunaegyo in the adjacent Sunae-dong on safety concerns. Officials plan to conduct emergency safety inspections of the three bridges as soon as possible, and will ultimately carry out safety checks of all 211 bridges across the city.