Four Israeli soldiers have been wounded after a roadside bomb exploded in the occupied Syrian Golan Heights on Tuesday.
The Israeli army said it fired on Syrian army positions on the other side of the border in retaliation.
It was not clear who had planted the bomb.
Violence in Syria has spilled over into the Golan Heights previously but these are the worst casualties Israel has suffered there since the Syrian uprising began three years ago.
Israel captured the Golan from Syria in the 1967 war and annexed it in a move the rest of the world has never recognised.