Unknown gunmen opened fire on a Saudi police patrol in the kingdom's restive oil-rich east, wounding one officer, a spokesman said on Sunday.
The incident took place late on Saturday in the province of Qatif, just two days after a man was killed during clashes with Saudi security forces in a nearby town.
"During a routine patrol...the (police) were fired upon by unknown assailants... wounding one of the police officers," the regional police spokesman said in a statement published on the official SPA news agency.
He said the wounded officer was transferred to a hospital but gave no further details on his condition.
On Friday, Saudi security forces clashed with Shiite protesters in the provincial town of Awamiya after a police patrol was attacked with a petrol bomb, leaving the car in flames.
The interior ministry said unknown gunmen opened fire on police officers trying to control the flames, forcing a response from the security forces.
One person was killed in the exchange of fire.
Witnesses meanwhile said security forces opened fire with live rounds after Shiite protesters hurled stones at one of their vehicles.
Activists said Issam Mohammed, 22, was killed by multiple bullet wounds, and three other people were wounded.
Friday's clashes came after demonstrations in four Qatif region villages calling for the "release of political detainees, reform and an end to sectarian discrimination," one activist told AFP on condition of anonymity.
Protests erupted in the Eastern Province in March when members of the kingdom's Shiite minority took to the streets to condemn Saudi military intervention against Shiite-led pro-democracy demonstrations in neighbouring Bahrain.
Four Shiites were shot dead in November. The interior ministry said security forces had come under fire from gunmen operating on "foreign orders," in a veiled accusation against Shiite Iran.
Most of Saudi Arabia's estimated two million Shiites live in the Eastern Province. They complain of marginalisation in the Sunni-dominated kingdom.