At least one person was killed and three others wounded Monday when two mortar shells, likely fired from Syria, landed near a school in the Turkish town of Kilis on the border, officials said.

The mayor of Kilis, Hasan Kara, was quoted as saying by Turkey’s NTV television that all schools in the town had been evacuated and the shelling had most likely come from Syria.

One of those wounded was in a serious condition, he added.

Television pictures showed the wounded being taken to hospital by ambulance. Windows on the ground floor of the school had been smashed by the impact of the blast while one car was severely damaged.

Reports said that the person killed was a school cleaner. The shells reportedly landed in the garden outside the school.

“It seems that the shelling came from the south,” said Kara. “The people should not allow provocations. Kilis residents should stay calm.”

Kilis, a town of just under 100,000, lies just north of the Syrian border, some 10 kilometers (six miles) from the Syrian town of Azaz.

Turkish officials have said it is the only town in Turkey with a majority of Syrians, some of the estimated 2.2 million living in Turkey who have fled the civil war at home.

That area of northern Syria south of Kilis has in the last months been the scene of fierce clashes involving Islamic State (ISIS) jihadists who have seized swathes of northern Syria.

Turkey has said that it is working to push ISIS out of the border zone, which the extremist group controlled on the Syrian side for much of 2015.

A suicide bomber who the Turkish authorities say was a member of ISIS last week killed 10 German tourists in the center of Istanbul, the first time that foreigners have been targeted by such an attack in Turkey.

Turkish ground forces then pounded some 500 positions of ISIS in Syria and Iraq with artillery and tank fire over a 48-hour period, Prime Minister Ahmet Davutoglu said.

Turkey has often been criticized by its Western allies for not doing enough to combat ISIS jihadists, who have often entered in and out of Syria through Turkey.

But Ankara last year stepped up its involvement in the US-led coalition against ISIS, hosting American war planes at its Incirlik air base for deadly raids against the jihadists and conducting air strikes of its own.

Turkish media reports have said Turkish jets are no longer flying over Syria, after the shooting down of a Russian war plane on November 24 by one of Turkey’s jets led to an unprecedented crisis in relations between Moscow and Ankara.

Turkey has also repeatedly said it does not want Kurdish militia forces – who are themselves bitterly opposed to ISIS – advancing westwards of the Euphrates River in northern Syria.

Davutoglu said last week that Turkey would carry on fighting ISIS “until it leaves the Turkish border area completely.”

AFP contributed to this report.