A member of the Palestinian security forces was killed and three others seriously wounded on Thursday by an IDF tank shell during the second day of intense ground operations in the central Gaza Strip. Early Thursday morning, the IDF began distributing flyers throughout Gaza, calling on residents who have ammunition caches in or under their homes to leave their homes ahead of IDF strikes in the area. Defense Minister Amir Peretz ordered a general closure imposed on the West Bank and the Gaza Strip due to intelligence alerts indicating that many suicide attacks were being planned against Israeli civilians. The closure was ordered until Saturday night. On Wednesday evening, the Air Force resumed its attacks on the Mughazi refugee camp in the central Gaza Strip, killing one Palestinian and injuring 20 others, the IDF said. In Nablus, three Palestinians were killed earlier Wednesday during an IDF operation. The three were killed in an exchange of fire in a Palestinian prison between Palestinian operatives and IDF troops, said a spokeswoman for Nablus Governor Said Abu Ali. The spokeswoman, Anan Atiri, said she had seen the bodies herself but did not know the identity of the men. Earlier in the day, a Palestinian policeman was also reportedly killed during a firefight with IDF forces, who surrounded the Mukata compound and bulldozed part of the building where fugitives were hiding. Meanwhile, in the south, five IDF soldiers were wounded during operations in the central Gaza Strip after Israeli tanks moved into the Mughazi refugee camp early Wednesday morning, under cover of machine gun fire from troops. Two of the soldiers were wounded moderately, and the other three lightly, as a result of a grenade hurled by Palestinian operatives. The wounded soldiers were evacuated by helicopter. Residents said 30 Israeli armored vehicles were in the Gaza camp at sunrise. Soldiers took over several rooftops as bulldozers leveled farmland. The Israeli military confirmed that an operation was in progress. Palestinians said six Hamas gunmen were killed trying to fire a rocket at Israeli tanks and five were wounded in the clashes. Israeli aircraft fired two missiles at fugitives, they said. Fourteen people, including children, were wounded when tank shells hit two houses in the camp, hospital officials said. The camp, with 22,000 residents, is near the Gaza-Israel fence and across from the Palestinian town of Deir al-Balah. IDF forces operated in the region late last week before withdrawing. Israeli troops have also swept through southern Gaza and carried out two invasions of northern Gaza, trying to stop terrorists from firing rockets at Israel. The incursion was preceded by several hours of tank movements on the Israeli side, as well as exchanges of fire between soldiers and Palestinian gunmen. No casualties were reported. Israel began a large-scale operation in Gaza on June 28, three days after Hamas-linked operatives tunneled under the border and attacked an Israeli army base at a Gaza crossing, killing two soldiers and capturing Gilad Shalit. On Tuesday, a team of United Nations envoys met with Palestinian Authority President Mahmoud Abbas in Gaza City about the Israeli offensive in the territory.