A Saudi lawman was killed and two others were wounded during an attack in a Shiite-dominated area of Eastern Province, the interior ministry said today.
"One policeman was killed and two injured," an interior ministry spokesman said.
In a statement, police said two suspects were arrested after the patrol came under fire in al-Jesh village of Qatif district yesterday.
"The motive of the crime is not clear yet, and we are waiting for the investigation results," the spokesman said.
Two residents of the area told AFP that similar incidents have been linked to criminal activity including the drug trade.
Eastern Province was also the scene of periodic clashes involving security forces after demonstrations broke out four years ago alongside a Shiite-led protest movement in neighbouring Bahrain.
Most of Saudi Arabia's Shiites live in the oil-rich east, where many say they face marginalisation.
Since late last year, the eastern region has been targeted by the Islamic State group, Sunni extremists who consider Shiites to be heretics.
Authorities and analysts say the jihadists tried to ignite sectarian tensions in the Sunni-majority kingdom but failed.
On successive Fridays in May suicide bombings at Shiite mosques in Eastern Province, one of them in Qatif, killed a total of 25 people.
An IS-affiliated group calling itself Najd Province -- which takes its name from the region around Riyadh -- claimed those attacks as well as another suicide bombing that killed 26 people at a Shiite mosque in Kuwait last month.
Since the mosque bombings, local Shiite volunteers, backed up by police, have increased security in Saudi Arabia's east.
Saudi security forces have themselves been targets of attacks linked to IS, which has committed atrocities in Iraq and Syria and inspired attacks elsewhere around the world.
On July 18 the interior ministry announced it had disrupted a network linked to IS and made more than 430 arrests, foiling new attacks on Shiite mosques and a diplomatic mission.
Two days earlier, a car bomb exploded at a security checkpoint near a prison in the Saudi capital Riyadh. It killed the 19-year-old driver and wounded two policemen, the interior ministry said.
In the southwestern city of Taif on July 3, a policeman was gunned down during a raid in which three people were arrested and flags of the IS group found, police said earlier.
A Western diplomat said the kingdom's security forces have been "quite efficient" in their effort against extremists.
