The Islamic State group's radio station has claimed responsibility for a suicide bombing Friday on a Shiite mosque in Saudi Arabia, warning that more "black days" loom ahead for Shiites.
The attack killed at least 21 people and wounded dozens in the eastern town of Qatif as worshippers commemorated the birth of a revered saint.
The statement on the Islamic State group's al-Bayan radio station, read aloud Friday night and posted Saturday morning to militant websites associated with the extremists, identified the suicide bomber as Saudi citizen Abu Amer al-Najdi and posted a purported picture of him.
The station also identified the attack as being carried out by a new branch in "Najd Province," referring to the historic region of the central Arabian Peninsula home to the Saudi capital, Riyadh.