GAZA CITY, Gaza Strip - Defiant Palestinian militants pounded Jewish settlements in the southern Gaza Strip with mortar fire today after the killing of a top Hamas militant in an Israeli airstrike.

The Islamic militant group threatened attacks on Israel to avenge Adnan al-Ghoul, a founder and deputy chief of the Hamas military wing. A lower-ranking militant was also killed in the airstrike Thursday night.

Al-Ghoul, 46, was a top bombmaker and was responsible for Hamas' weaponry, including anti-tank missiles and Qassam rockets the group has been firing at Israeli communities, the Israeli army said. Held responsible for the deaths of dozens of Israelis, he had escaped previous attempts on his life.

Following the killing of al-Ghoul, around 15 mortar rounds were fired at the Jewish settlement of Neve Dekalim and adjacent military posts, damaging four houses but causing no casualties. Settlers reported mortar shells falling on two other south Gaza settlements, but causing no damage.

One militant was killed and another gravely injured as they prepared to fire a mortar at Neve Dekalim, Palestinians and the army said. Palestinians said the dead man was a known Hamas activist. It was not yet clear if the men were hit by Israeli fire or whether the mortar shell exploded prematurely.

Al-Ghoul had been in hiding for years, avoiding public appearances.