Turkish shelling and air strikes killed at least 40 Syrians on Sunday, a monitor said, in the first significant civilian casualties in Turkey’s intensifying campaign in northern Syria.

Turkey’s state-run Anadolu news agency said the army had killed 25 Kurdish “terrorists” in air strikes as part of its unprecedented operation inside Syria.

The bombardments came after Ankara suffered its first military fatality since it launched the two-pronged offensive against the Islamic State group and Syrian Kurdish militia inside Syria on Wednesday.

At least 20 civilians were killed and 50 wounded in Turkish artillery fire and air strikes on the village of Jeb el-Kussa early on Sunday, the Syrian Observatory for Human Rights monitoring group said.