A man whom the U.S. described as a key figure in Al Qaeda in the Arabian Peninsula accidentally blew himself up, U.S. military officials told Fox News.

The officials say Nayif Al-Qahtani was “messing with a bomb” when it went off. U.S. officials had been watching him, but Fox News’ sources insist the U.S. had nothing to do with his death.

Al-Qahtani was “a vibrant guy linked to ongoing operations planning, and his death will have an impact,” one official told Fox News.

An Al Qaeda in the Arabian Peninsula newsletter was the first to announce his death a week after the United States put terror sanctions on him. The newsletter did not say when it happened but said Al-Qahtani died in Yemen’s Abyan province in the south of the country.

The State Department recently described al-Qahtani as “a liaison between Al Qaeda cells in Yemen and Saudi Arabia.” It said he manages Al Qaedain the Arabian Peninsula’s operations in Yemen and receives financial support from abroad to launch attacks in both Yemen and Saudi Arabia.