A bomb has exploded outside a Shia mosque in Saudi Arabia, reportedly killing at least four people.
Officials said that a suicide bomber blew up a car in the city of Dammam in Eastern Province.
The Islamic State (IS) group has said that it was behind the attack in a statement released on social media.
At least 21 people were killed in a similar incident one week ago, when a suicide bomber struck during Friday prayers at a Shia mosque.
The attack at the Imam Ali mosque in the village of al-Qadeeh was the first to be claimed by the Saudi branch of IS, which was formally established last November.
In Dammam on Friday, a suicide bomber detonated his explosive device outside the al-Anoud mosque in a busy neighbourhood.
A witness told Reuters that he had seen a "quick explosion" and that he had been told that men had prevented the attacker from getting inside the mosque.
Security forces had become suspicious of a man in a car near the mosque and had gone to investigate it. It exploded as they approached the vehicle, according to the Saudi Press Agency (SPA).
One of those killed is believed to have been the driver of the car.
In a statement published online, IS said "a soldier of the Caliphate" was behind the attack on the Shia community. It identified the bomber as Abu Jandal al-Jazrawi.
Saudi Arabia has previously been threatened by IS. It is part of a US-led coalition against IS in Syria and Iraq.
The Saudis are also leading a coalition of Arab states in an air campaign against Shia rebels in Yemen.
The country's large Shia Muslim minority is mainly based in the Eastern Province, and there have been sporadic protests by Shia there to call for more rights.