Saudi Arabia's Interior Ministry says unknown gunmen killed two security officers in the eastern city of Dammam, an area heavily populated by Shiites.

The ministry's spokesman Maj. Gen. Mansour al-Turki said in a statement carried Sunday by the official Saudi Press Agency that a patrol in Dammam's al-Khudariya district came under fire late Saturday night.

Last month, Dammam police arrested two men, one Saudi and the other Syrian, in possession of a firearm and an explosive vest who were allegedly recruited by the Islamic State group to carry out a suicide attack. Two other Syrians were also arrested.