The official Saudi Press Agency says a suicide bomber blew himself up near a Shiite mosque in an eastern Saudi city and killed four people.
It said the bomber tried to enter the Mosque in Dammam, a Shiite-dominated city, during Friday prayers and detonated his bomb in the parking lot after being stopped by security guards.
It added that guards approached the car as it was parking and that the driver detonated the bomb. It was unclear if the bomber was among the four.
It was the second attack against a Shiite mosque in Saudi. An attack last week killed 21 people and the Islamic State extremist group claimed responsibility for the attack.