A Saudi special forces officer was killed and three others injured on Thursday morning while on duty in eastern Saudi Arabia, Saudi news site Sabq reported.
The attack occurred in al-Awamiya, located in the oil-producing al-Qatif province, a flashpoint between the Sunni Muslim government and minority Shi'ites complaining of discrimination. No further details were immediately available.
A rocket-propelled grenade attack in the same old part of the city, al-Musawara, killed a soldier and wounded three others two days ago.
Saudi authorities have been bulldozing al-Musawara, a small part of the town with narrow streets which date back more than 200 years, to make way for a new project.
Local officials say wanted militants believed to be behind attacks on security forces have been using the narrow streets to escape arrest.
Saudi Shi'ites complain of discrimination by the government, a charge that authorities deny, and have carried out protests for more rights for the last several years.
Demonstrations and attacks have both become more frequent since Nimr al-Nimr, a Shi'ite cleric convicted of involvement in violence, was executed a year ago.