Israel ? Israeli forces killed 19 Palestinians in the Gaza Strip on Tuesday, most of them Hamas fighters, in an armored raid and air strikes that the Palestinian Authority called “a slap in the face” of stepped-up peace efforts by President Bush.

The Palestinian death toll, which included the son of Mahmoud Zahar, a hard-line Hamas leader, was the highest in a single day in Gaza since late 2006. Three of the dead were civilians, and more than 40 people were wounded, a dozen seriously.

The Israeli army said its assault was meant to push militants back from the border fence and prevent rocket and mortar attacks on Israel, but the raid triggered a deadly cross-border shooting and renewed rocket and mortar fire. A 20-year-old volunteer from Ecuador working in the fields of an Israeli kibbutz near the Gaza Strip was killed by Palestinian sniper fire across the border fence. Hamas claimed responsibility.