Saudi authorities arrested nine people accused of wounding three policemen in the oil-rich east, home to much of the kingdom's Shiite minority, the interior ministry announced on Tuesday.
"Security forces raided late on Monday one of the hideouts in Qatif of nine people behind these events," said a ministry statement carried by the official SPA news agency.
It was referring to what it said were two separate attacks, on January 14 and 18, in which "three members of the security forces were wounded" when "unknown gunmen opened fire on their patrols" in Qatif.
Authorities had announced the January 14 attack but it was the first official mention of violence on January 18.
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The January 14 shooting came just two days after a man was killed in clashes with Saudi security forces in the town of Awamiya in the Qatif region.
Those clashes came as Shiites celebrated Arbaeen, which marks 40 days after Ashura, the annual commemoration of the slaying of Imam Hussein, one of Shiite Islam's most revered figures, by the armies of the caliph Yazid in 680 AD.
Earlier this month, authorities published a list of 23 men wanted on suspicion of involvement in disturbances in Shiite areas of the kingdom in recent months.
Protests erupted in the Eastern Province in March when Shiites 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.