At least 13 Palestinians, most of them civilians, were shot dead and others wounded by Israeli gunfire in the Gaza Strip, Palestinian medical sources said Wednesday. They added many other Palestinians were injured. During an Israeli raid into Alzaytoun area, south of Gaza City, Palestinian fighters exchanged fire with occupation troops. At least nine Palestinians were killed, including a 10-year-old boy. Eyewitnesses told IPC that Israeli troops denied ambulances and medical crews access to the area. In addition, a Palestinian paramedic was injured when Israeli troops opened fire on an ambulance carrying some of the victims to hospital. Earlier it was reported that Israeli occupying forces moved into the area under a barrage of heavy gunfire as bulldozers razed vast areas of lands. Elsewhere in the Strip, the Israeli army said that troops spotted five armed Palestinians approaching an army patrol operating near the settlement of Netzarim. Soldiers fired towrds them and killed four. The Islamic Jihad group said at least four of its fighters were killed and vowed to avenge their deaths. "The bloody message has been received...and the Palestinian people will know how to respond to it," said Mohammed Al-Hindi, a leader of the Islamic Jihad. The Islamic Jihad identified its four dead fighters as Othman Jundiyyeh, 21, Marwan Attiyyeh Basel, 38, Eyad Mahmoud al Ra'i, 39, and Musa Suleiman Dalul, 31. Member of the Executive Committee of the Palestine Liberation Organization (PLO), Yasser Abed Rabbo, condemned the Gaza city "massacre." "The invasion of Gaza City at this timing and under the current circumstances comes within the context of the endeavors of the (Israeli) government of (Prime Minister Ariel) Sharon to foil the efforts of regional and international mediators to calm down the situation, as well as the peaceful efforts of both Palestinian and Israeli peace advocates," Abed Rabbo said in a press release on Wednesday. Abed Rabbo added that the "crazy" military escalation by Sharon's government is also "a desperate attempt to cover up the series of corruption and bribe scandals embroiling Sharon and his sons." Sharon also aims "at diverting Israeli and world public opinion away from the Wall of settlement, annexation and expansion which his government continues to build despite escalating international criticism and protests," Abed Rabbo added. He further called on the world community, the United States in particular, to urgently intervene to put an end to the Israeli escalation and to pressure Israel into fulfilling its commitments stipulated in the "roadmap" peace plan, "instead of rewarding Sharon by extending an open invitation to him to visit the White House," Abed Rabbo concluded. **PHOTO CAPTION*** Palestinian medical staff bring a wounded Palestinian man into the Red Cross hospital in Gaza City January 28, 2004. (REUTERS/Nayef Hashlamoun)