The blast from an explosive device hit late Sunday a police patrol killing a major and wounding two others in the restive Qatif province dominated by Shias who have been staging recurrent protests over marginalization.
State-run news agency SPA citing the interior ministry reports that the blast occurred in the Masoura district of the province.
The police major has been identified as Tareq al-Alaqi. The wounded security forces are in stable condition, the interior ministry noted.
Late last month, another bomb blast in the eastern Awamiya town injured two police personnel; an incident that followed the death of a soldier nearly two weeks earlier. Five other soldiers were wounded in the attack.
Shia militants have been resisting construction and rehabilitation projects in Awamiya, after Saudi authorities decided to raze the old town used by terrorists and gunmen as hideout for illegal activities including drug and arm dealing.
Authorities say old buildings will be replaced by shopping centres, office buildings and green spaces.
The town has been flashpoint between Saudi security forces and the Shia minority, which complains of marginalization. Riyadh muted protests in the area in 2011 as the Shia stood for more rights.
Tensions flared up following the execution of Shia cleric Nimr al-Nimr a year ago.