JERUSALEM, Aug. 22 -- A four-year-old boy was killed on Friday evening by a mortar attack on southern Israel, Magen David Adom, Israel's Red Cross, told to Xinhua.

The child was killed when a mortar barrage launched from the Gaza Strip hit a car near a kindergarten in Sdot Negev Regional Council near the Israel-Gaza border, said a spokesperson with the Israeli military.

It is the first Israeli casualty since a fresh round of fighting between Israel and Hamas, the Islamist group who dominates Gaza, had started on Tuesday.

Israel's Prime Minister Benjamin Netanyahu vowed a tough response to the killing, saying "Hamas will pay a heavy price for this terror attack."

The boy was the first juvenile causality to die on the Israeli side since Israel embarked on the operation "Defense Edge" in Gaza. Sixty eight Israelis have died, 64 of them were soldiers.

Israel and Hamas resumed the fighting after the indirect negotiations in Cairo, aiming at achieving ceasefire in the hostility which began onJuly 8, had collapsed on Tuesday.