ISTANBUL — Turkish artillery pounded Kurdish militant targets in northern Syria for a second day on Thursday, with both sides reporting civilians were killed, and President Recep Tayyip Erdogan slammed Western nations for failing to support the incursion into a neighboring country.

Turkey’s attack on a roughly 120-kilometer (75-mile) stretch of Syrian territory south of its border has sparked an international backlash, with the United States — which has supported the Kurdish-dominated Syrian Democratic Forces (SDF) for half a decade in the fight against the Islamic State — threatening economic sanctions and the European Union demanding Turkey halt the military action or risk unleashing more turmoil in the region.

An infant and an employee at a tax office were killed by mortar fired launched from Syria that hit two Turkish towns on the border, the provincial governor said in a statement. More than a dozen other civilians were wounded when shells struck a total of four towns, reported the Anadolu news agency.

Across the border, the Kurdish Red Crescent said seven civilians were killed. The Syrian Observatory of Human Rights said more than 60,000 civilians have fled the fighting and put the death toll of SDF fighters at 23. Erdogan said 109 SDF militants had been “neutralized” and denied Syrian civilians had perished. The Defense Ministry reported no Turkish soldiers had died.