An Israeli airstrike killed two Palestinian militants in the northern Gaza Strip Sunday afternoon just after they fired rockets at Israel, the Israeli military and hospital officials said.

In all, Israel killed four Palestinian militants in Gaza on Sunday.

The Israeli military said its aircraft hit a rocket launching site after militants fired rockets at Israel, hitting them.

Abu Hamzeh of Islamic Jihad said the two men belonged to the group and "were on a holy mission."

Two rockets fired from northern Gaza exploded in the Israeli town of Sderot just across the fence, wounding an Israeli and damaging a sports center and a house, the Israeli rescue service said. Islamic Jihad claimed responsibility.

After nightfall an Israeli aircraft fired a missile at a car in Gaza City, witnesses said, but missed. No one was hurt. The Israeli military said the target was an Islamic Jihad militant.

Earlier in the day, Israeli troops operating in the northern Gaza Strip shot and killed two Hamas gunmen, the militant group and the military said.

The Hamas fighters were trying to ambush the Israeli soldiers who entered the Gaza Strip, Hamas said.

The soldiers entered the Gaza Strip a few meters (yards) to as they conducted a "routine patrol" northeast of the Palestinian town of Beit Lahiya against attempts by militants to tunnel into Israel and carry out attacks against troops, the military said.

Israeli airstrikes at Palestinian militants and rocket launchers in Gaza are becoming more frequent, as the daily rocket barrages on Israeli towns continue.