Saudi Arabia's interior ministry has confirmed that two people were killed after the Imam Reza mosque in the country's eastern region was attacked by a suicide bomber. "As a result of the suicide bomber, two people were martyred and seven wounded," the ministry said, according to AFP.

The number of fatalities, however, is believed to be three and is expected to rise, as some of the injured being treated are in critical condition. This latest figure is still unconfirmed as authorities have yet to make a formal announcement.

The details of the attack are still sketchy at this stage, but initial reports citing eye witnesses reveal that the attack involved shootings and the suicide bomber was purportedly apprehended by angry worshippers before he was taken into police custody, the Associated Press reported. The video below showing an angry mob being driven back by the police seems to corroborate this. Other sources also stated that the gun attack was preceded by a bomb explosion, according to Al Jazeera.

No group has so far claimed responsibility for the attack. However, the Islamic State has been targeting the Shiite ethnic group, which constitutes as a minority in the Sunni-dominated country. The militant organization believes that the Shiite are heretics. A prominent cleric from this group was also executed by the government earlier this month.