A suicide bomber blew himself up in the parking lot of a Shiite mosque in eastern Saudi Arabia during Friday prayers, killing four people in the second such attack in as many weeks claimed by ISIS.
The attack, which set vehicles alight and sent a cloud of black smoke into the air, came after a suicide bombing a week ago at another Shiite Muslim mosque killed 21 people, heightening sectarian tensions in the Sunni-majority kingdom.
Both attacks took place in the oil-rich east, which has a sizable Shiite majority that has long complained of discrimination. ISIS and other Sunni extremists view Shiites as apostates deserving of death.
There were conflicting reports of the attack, which took place after worshippers packed the Imam Hussein mosque, the only Shiite mosque in the port city of Dammam.
The state-run Saudi Press Agency said security guards halted a car in the parking lot of the mosque and that the bomber detonated his payload as they approached.
"Thank God, security authorities managed to foil a terrorist crime targeting worshippers," the agency said in a statement. It was unclear if the bomber was among the four dead.
A security official told The Associated Press that the attacker had disguised himself in the black all-encompassing garments worn by women in Saudi and blew himself up after being stopped by security guards. He insisted on anonymity because he was not authorized to speak to the media.