Turkish warplanes mistakenly killed 35 smugglers and other villagers in an operation targeting Kurdish terrorists in Iraq, a senior official said Thursday, one of the largest one-day civilian death tolls during Turkey’s 27-year drive against the terrorists.

Huseyin Celik, a spokesman for Prime Minister Recep Tayyip Erdogan’s ruling party, said authorities were still trying to identify the dead, but that most were youngsters from an extended family in the mostly Kurdish-populated area that borders Iraq.

All of the victims were under age 30 and some were the sons of village guards who have aided Turkish troops in their fight against rebels, he said.

“According to the initial information, these people were not terrorists but were engaged in smuggling,” Celik said, adding that Turkey was ready to compensate the victims. “If there was a mistake, if there was a fault, this will not be covered up, and whatever is necessary will be done.”