A Saudi affiliate of the Islamic State group said Tuesday it was behind the assassination of a police colonel who was shot dead outside the capital, Riyadh, in the second attack by the group in recent days.

The Saudi Interior Ministry confirmed in a statement that Col. Kitab Majid al-Hammadi was shot dead Tuesday around 8:30 a.m. in the area of al-Dawadmi, located 124 miles west of Riyadh. The Interior Ministry said the shooter's identity is unknown and that it is investigating the incident.

The statement issued by ISIS' Najd Province also named the colonel its militants shot dead, saying he worked in the Interior Ministry's General Investigation unit. Najd Province is the traditional name for the central heartland of the Arabian Peninsula and the homeland of the ruling Al Saud family.

On Sunday, the local affiliate said it was behind an explosives' attack outside a police station Saturday that set fire to three police vehicles in the city of al-Dalam, located 62 miles southeast of Riyadh. Saudi police said a civilian, identified by local media as an Indian laborer, was killed in that explosion.

The targeted assassination, however, represents a shift in the way the Najd Province affiliate has carried out attacks as police crackdown against extremists following a string of major bombings. Last year, the Najd Province affiliate claimed responsibility for three bombings of Shiite mosques that killed 53 people in eastern Saudi Arabia and Kuwait.

Since then, hundreds of suspects have been arrested and several have been tried for having ties with ISIS. Saudi Arabia is also part of the U.S.-led coalition bombing the ISIS group in Iraq and Syria.

Another local ISIS-inspired group, calling itself the Hijaz Province affiliate, was behind a mosque bombing inside a police compound that killed 15 people in August. Meanwhile, ISIS' Bahrain Province affiliate claimed responsibility for a shooting in eastern Saudi Arabia that killed five worshippers in October.

A similar attack in late January outside a Shiite mosque in eastern Saudi Arabia killed four people, though no group claimed responsibility. Last month, Saudi police killed six men they said were wanted for the murder of a counter-terrorism security officer, whose death was filmed and posted online by the suspects who declared their allegiance to ISIS and its leader Abu Bakr al-Baghdadi.