Security forces were on a heightened state of alert because of the Saudi-led campaign against Houthi rebels in Yemen
Unknown gunmen shot and injured two policemen in a patrol car in Saudi Arabia's capital Riyadh late on Sunday, the state-owned Saudi Press Agency quoted a police spokesman as saying on Monday.
Police are conducting an investigation into the shooting, which came from another car, the spokesman added. He said the injured officers were being treated in hospital and were in a stable condition.
Saudi Arabia's security forces have in the past been targeted by Sunni Muslim jihadists such as Al Qaeda and supporters of the ISIL group across the country. They have also been targeted by some radical members of the Shi'ite minority in the Qatif area in Eastern Province.
Saudi authorities said on Thursday the security forces were on a heightened state of alert because of the Saudi-led campaign against Houthi rebels in Yemen.