Al Qaeda's Yemen branch has claimed responsibility for the murder of American teacher Joel Shrum, in a statement posted on its website Thursday.

The 29-year-old Pennsylvania native was executed in a hail of bullets from two men on a motorcycle who pulled up alongside his car, Sunday in Taiz.

The group accused Shrum of "proselytizing."

"It was God's gift for the mujahedeen to kill the American Joel Shrum who was actively proselytizing under the cover of teaching in Taiz," said al Qaeda in the Arabian Peninsula, for formal name for the terror network's Yemen branch.

The death of Shrum, who was well-respected in the community for his efforts to help the region's poor, has sparked protests from Yemeni youth and activists who knew him.

"Joel served the city of Taiz and was a good friend who came from the United States," activist Radwan al-Qadri said at Tuesday's rally.

"[He] was a lovable person who respected humanity and was himself respected," he added.

The U.S. State Department has condemned Shrum's murder as an act of terror.