The Israeli army has fired tank shells into the Khan Yunus refugee camp in the southern Gaza Strip wounding up to six Palestinian schoolchildren. The children, four seven-year olds and two nine-year olds, suffered shrapnel wounds when one of the shells exploded in the yard behind their school, Palestinian officials said. The army had no immediate comment. The tank attack came after Palestinian resistance fighters fired a mortar shell at an Israeli target in the southern Gaza Strip, causing no damage or injuries, the army said. Settlers said resistance fighters had fired two other projectiles at a settlement near Khan Yunus overnight. Settlements are illegal under international law. Israeli forces have remained deployed around Khan Yunus since Friday when they raided the vast refugee camp. On Friday, Israeli troops killed a seven-year-old Palestinian girl in southern Gaza. Rania Siam died of a bullet wound to the head. Aljazeera learned that the incident took place when Israeli forces fired randomly at Palestinian homes in the town. The firing of mortar shells and rockets at settlements in Gaza and nearby towns in Israel has threatened Israeli Prime Minister Ariel Sharon's plan to withdraw from the Gaza Strip next summer. **PHOTO CAPTION*** A Palestinian girl holds a picture of her jailed father during a demonstration calling for the release of Palestinian prisoners held in Israeli jails, at the Red Cross office in the West Bank city of Nablus, December 11, 2004. (REUTERS)