The Israeli army killed at least four Palestinian gunmen and five civilians in air and ground strikes in the Hamas-controlled Gaza Strip on Thursday, witnesses and hospital officials said.

Hamas said one of its militants was killed and three were wounded by an Israeli missile in the central Gaza Strip after they had tried to fire mortar bombs into Israel.

Another militant with Hamas, an Islamist group, was killed and three were wounded by a missile attack on a militant training camp near the southern town of Rafah, Palestinian hospital staff and a Hamas official said.

An Israeli army spokeswoman confirmed there had been a missile attack on a gunman in the central Gaza Strip and said she was checking the report of the Rafah strike.

An earlier incursion by Israeli troops near the town of Khan Younis was a hunt for militants who fire short-range rockets into Israel, the Israeli army said.

One rocket fired on Thursday landed north of the Israeli city Ashkelon, 17 km from Gaza -- the furthest a Palestinian rocket has ever penetrated into Israel, the army said. A second landed in the garden of a house in Sderot, a police spokesman said.

After the Ashkelon attack, which caused no casualties or damage, Israeli warplanes bombed three buildings in the Gaza Strip, causing extensive damage.

Two of the buildings were linked to the militant group Islamic Jihad and the third to Hamas, an Israeli military spokeswoman said.

Palestinian witnesses and medical officials said an Israeli tank fired at a house near Khan Younis, killing an Islamic Jihad militant outside. The shell also killed his mother, a sister and two brothers, who were in the house at the time.

An Israeli military spokeswoman said troops had come under attack by local gunmen. A tank fired at a building after gunmen were spotted taking shelter in it, she said.

Another shell wounded at least seven schoolchildren between the ages of eight and 10, hospital officials said. Medics said an Israeli tank fired the shell into a crowd. The Israeli army said it was checking the report.

The army killed two Hamas gunmen in separate incidents, both sides said, and wounded 22 Palestinians, most of them gunmen.

U.S. President George W. Bush visits the region next week to build on the November peace conference in Annapolis, Maryland, at which Israeli Prime Minister Ehud Olmert and Palestinian President Mahmoud Abbas pledged to pursue talks.

ROCKET WORRIES

The rocket attack on Ashkelon stirred concern in Israel, which says Palestinian factions are smuggling in military grade munitions from neighbouring Egypt.

Islamic Jihad and another Palestinian militant group, the Popular Resistance Committees, claimed responsibility for the rocket. A rival claim, with a videotape claiming to show the rocket launch, was made by the militant Popular Front for the Liberation of Palestine -- General Command.

"Until now it was only the population immediately adjacent to the Gaza Strip that was in the immediate firing line, (but) because of the extended range we could have as many as 250,000 Israelis in the firing line," said Olmert spokesman Mark Regev.

Hamas seized control of the Gaza Strip in June after routing Abbas's Fatah forces but Fatah runs the occupied West Bank.