South Korea's Marine Corps apologized to the family of a lance corporal who died after being swept away in a stream during a search and rescue for victims of heavy monsoon rains.

In a message to the defense ministry press corps on Thursday, the Marine Corps offered prayers for the repose of the deceased Marine, who lost his life while fulfilling his duties, and conveyed condolences and apologies to his family.

The military branch said it has opened an investigation into the case and plans to take follow-up measures while giving the most honorable treatment to the servicemember who died in the line of duty.

It added that a general inspection is also under way to assess the safety management of units dispatched to the search and recovery.

On Wednesday, the lance corporal disappeared in the rapids of the Naeseong Stream in Yecheon County, North Gyeongsang Province while participating in the search operation in which no soldiers reportedly wore life jackets.

The body of the missing Marine was discovered 14 hours later, some six kilometers downstream from where he was last seen.