Gunmen have opened fire on a Saudi checkpoint in a Shiite village in the Gulf state's oil-rich Eastern Province, wounding a policeman, police said on Tuesday.
The attack in Awamiya came at around midnight on Monday, state news agency SPA cited the province's police spokesman as saying.
It came two days after police in the mainly Sunni kingdom killed a man wanted on "terror-related" charges in a firefight in the same village.
Awamiya, just west of Dammam city, has seen several clashes between security forces and Shiite protesters.
In early September, gunmen fired on a police patrol there, wounding one officer and causing a pipeline to catch fire.
Saudi Arabia's estimated two million Shiites, who have complained of marginalisation, live mostly in the east where the vast majority of the OPEC kingpin's huge oil reserves lie.
Demonstrations in Eastern Province first erupted in 2011 alongside a Shiite-led protest movement in neighbouring Bahrain.
They turned violent in 2012, and clashes have now killed at least 24 people, including at least four policemen.
In June, a court sentenced two people to death for "taking part in forming a terrorist group" and other crimes linked to the protests by Shiites.