The Saudi interior ministry vowed on Friday to arrest the masterminds behind a "cowardly" mosque attack that left 21 people dead in eastern Saudi Arabia. "The terrorist attack confirms that deviant groups are seeking to create chaos [in the Kingdom]," spokesman for the Saudi Ministry of Interior Maj. Gen. Mansour Al Turki told Al Arabiya News Channel, mentioning similar previous incidents including a shooting in the Eastern Province district of al-Ahsa last year. In November, three masked gunmen attacked a group of residents in al-Dalwah village in al-Ahsa, killing five people and injuring nine others. "What is important now is that we stop the masterminds behind this cowardly act and arrest them," Al Turki added. During the interview, Al Turki also said that security forces were able to foil a terror plot after arresting a cell made up of 65 people. On Friday, a suicide bomber blew himself up during prayers at a mosque in the village of al-Qadeeh in eastern Saudi Arabia, killing at least 21 and wounding 81 others. Injured worshippers were transferred to the Qatif Central Hospital and Aramco Hospital for treatment, according to health officials Responsibility Loyalists of the extremist the Islamic State of Iraq and Syria (ISIS) claimed responsibility for the attack - the second against Shiites in the kingdom in six months. In a statement distributed on Twitter feeds linked to ISIS group loyalists, a group purporting to be the "ISIS branch in Saudi Arabia" issued the claim. It could not be independently verified whether the group actually has operational links to ISIS, which is based in Syria and Iraq.