SEOUL - The Democratic People's Republic of Korea (DPRK) sent a notice to the Republic of Korea (ROK) on Friday to explain the deadly shooting of a ROK civilian by DPRK soldiers in the DPRK territorial waters, according to the South's presidential Blue House.

The United Front Department (UFD) of the Central Committee of the ruling Workers' Party of Korea of the DPRK sent a formal notice to the Blue House, saying that an unidentified man aboard a floating material, who illegally intruded into the western territorial waters of the DPRK, was shot dead on Tuesday evening, according to the Blue House.

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Kim Jong-un, chairman of the State Affairs Commission of the DPRK, expressed his apology to ROK President Moon Jae-in and ROK people for disappointing them with the unsavory case, the Blue House said

The UFD notice informed that the man, who crossed the inter-Korean sea boundary without approval, equivocated to verbal security checks by DPRK soldiers, according to the Blue House.

The DPRK soldiers shot two blanks before approaching the man and firing at him about 40-50 meters away, the Blue House quoted the UFD notice as saying.

The soldiers searched the floating material after the gunshots, only finding plenty of blood on it, without the man's body, so the DPRK military asserted that the man was dead, the Blue House said.

The floating material was burned according to the country's emergency quarantine guidelines, the Blue House quoted the UFD notice as saying.

The UFD also expressed regret over the ROK military's blasphemous, confrontational expression related to the incident.

It said the DPRK leadership saw what should not happen to occur, instructing the military to set up a system recording the entire process of sea guard activities in order to prevent any minor mistake or big misunderstanding during a crackdown process.

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The UFD said the DPRK side delivers its apology to the ROK side for the incident that may not have positive effect on the DPRK-ROK relations, according to the Blue House.

Kim Jong-un, chairman of the State Affairs Commission of the DPRK, expressed his apology to ROK President Moon Jae-in and ROK people for disappointing them with the unsavory case, the Blue House said, citing the UFD notice.

So far, the DPRK side has not reported the shooting incident publicly, nor commented on the ROK's unveiling of the UFD notice.