RAMADI, Iraq, March 22 (Xinhua) -- The Islamic State (IS) militants on Thursday killed four border guards in an ambush near the Iraqi border with neighboring Jordan, a security source said.

The incident occurred after midnight when the extremist militants opened fire on the car carrying the border guards, who were in civilian uniform, and killed them all on the main road near Trebil border crossing with Jordan, Major Mohammed al-Obeidi from the Border Guards Command told Xinhua.

Iraqi security forces launched a search campaign in the area looking for the attackers, Obeidi said.

During the past few months, dozens of IS militants fled their former urban strongholds near the borders of Syria and Jordan, as well as in other Iraqi provinces in north of Baghdad after the Iraqi forces carried out major anti-IS offensives.

However, remnants of IS militants resorted to hideouts in the vast desert in western Iraq and rugged areas in north and east of the country to continue their almost daily attacks against civilians and Iraqi forces.

On Dec. 9, 2017, Iraqi Prime Minister Haider al-Abadi officially declared full liberation of Iraq from IS militants after Iraqi forces recaptured all the areas once seized by the extremist group.

However, small groups and individuals of IS militants regrouped and are carrying out attacks against the security forces and civilians despite operations from time to time to hunt them down.