Three sons of Hamas leader Ismail Haniyeh have been killed in an Israeli airstrike in the Gaza Strip, the Palestinian group and Haniyeh’s family said, according to Reuters.

The Israeli military said it was checking the report.

Haniyeh has been the tough-talking face of Hamas’ international diplomacy as Israel’s military operation has raged on in Gaza, where his family home was destroyed in an Israeli airstrike back in November.

The three sons — Hazem, Amir and Mohammad — were killed after the car they were driving in was bombed in Gaza’s Al-Shati camp, Hamas said. Three of Haniyeh’s grandchildren were also killed in the attack, Hamas media said.

The three sons and three grandchildren were making family visits during the first day of Eidul Fitr in Shati, their home refugee camp in Gaza City, according to relatives.