TIKRIT, Iraq, March 21 (Xinhua) -- Six people were killed and 13 injured by the extremist Islamic State (IS) militants who opened fire on civilians on a main road near Iraqi ethnically mixed town of Tuz-Khurmato in Iraq's central province of Salahudin, a provincial security source said on Wednesday.

The incident took place late on Tuesday night when IS militants attacked a number of civilian cars outside a restaurant on the main road in north of the town of Tuz-Khurmato, some 90 km east of the provincial capital Tikrit, Major Ali al-Baiyati from Salahudin's provincial police told Xinhua.

Iraqi security forces launched a search campaign in the area looking for the militants, Baiyati said.

On Tuesday, IS militants set up a fake checkpoint on the main road near the mountainous Himreen area and kidnapped 10 policemen who were in two civilian cars heading to their homes in Baghdad for vacation.

During the past few months, dozens of IS militants fled their former urban strongholds in Mosul, Salahudin province and Hawijah area in the west of Kirkuk after the Iraqi forces cleared these areas during major anti-IS offensives.

However, remnants of IS militants resorted to hideouts in rugged areas near the rivers of Tigris and Zab, as well as Himreen mountainous areas 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 in the rugged areas and are carrying out attacks against the security forces and civilians despite operations from time to time to hunt them down.