Islamic State militants claimed responsibility for bombing the Shi'ite mosque in Saudi Arabia's city of Dammam in which four people were killed on Friday.
The explosion came from a parked car with witnesses saying that the suicide bomber was prevented from reaching the mosque.
Islamic State posted a statement on Twitter naming the suicide bomber who carried out the attack as Abu Jandal al-Jizrawi, saying he had managed to reach his target despite tight security.
Saudi Arabia has previously been threatened by ISIL. The country is part of a US-led coalition against ISIL in Syria and Iraq.