The death toll from an attack by the Islamic State group against an army checkpoint and people collecting truffles in central Syria has risen to at least 53, most of them civilians, state media and an opposition war monitor reported Saturday.

The attack near the central town of Sukhna on Friday was the deadliest by the extremist group since so far this year, the Britain-based Syrian Observatory for Human Rights, an opposition war monitor said.

The Observatory said the attack targeted a Syrian army checkpoint and people collecting wild truffles nearby, killing 68 people, including 61 civilians. It said IS fighters reached the area on motorcycles. On Friday, it reported that the attack killed 46.

The Observatory, which tracks Syria’s conflict, said the IS gunmen took advantage of the Feb. 6 earthquake that hit Turkey and Syria killing tens of thousands of people to carry out their deadly attack. The attention in Syria has been mostly focused on the earthquake over the past two weeks.

Syria’s state news agency, SANA, quoted the head of the general hospital in the central town of Palmyra as saying that they have received the bodies of 46 civilians and seven soldiers.

Despite their defeat in Syria in March 2019, Islamic State sleeper cells still conduct attacks around Syria and Iraq, where they once declared a “caliphate.”

On Friday, the U.S. military said a helicopter raid led by its forces in northeast Syria left a senior leader with the Islamic State group dead and four American service members wounded. It identified the killed IS commander as Hamza al-Homsi.

Joint operations between the U.S. military and Kurdish-led Syrian Democratic Forces are common in northeast and eastern Syria along the border with Iraq.