Hamas on Sunday called for new attacks on Israel after nine Palestinians were killed in a surge of fighting over the weekend. Hamas spokesman Fawzi Barhoum urged Palestinians to be prepared for a new round of confrontation. "The blood of our people is not cheap," he said in a statement faxed to The Associated Press. "Therefore we are calling on ... (Hamas's armed wing) and the Palestinian resistance groups to be united in the trench of resistance and to use all possible means of resistance and to respond to the massacres." Meanwhile, IDF troops on Sunday morning shot and killed a Palestinian youth near Ramallah as he prepared to throw a Molotov cocktail at the soldiers. Overnight Saturday, an IDF soldier was lightly wounded by gunfire during arrest operations in the West Bank city of Nablus, as troops killed two Al Aksa Martyrs Brigades operatives in the city. The two Aksa terrorists, including a top bombmaker, were killed in the Casbah of Nablus after IDF troops surrounded a building where they were hiding and ordered people out, the group said. Most occupants came out, but the two operatives remained holed up inside. An exchange of fire broke out, and the two men were killed. The group said the dead included Amin Lubadi, a bombmaker who had been wanted by the IDF for more than three years. Palestinian medical officials confirmed the deaths of two men. On Sunday morning, two Kassam rockets struck fired by Palestinian terrorists struck the western Negev, with one scoring a direct hit a Sderot home, lightly wounding three people. On Saturday night, IAF helicopters killed a member of a Kassam rocket cell in a car in the northern Gaza Strip, wounding one of his confederates. It was the second such missile strike since Israel accepted a Gaza cease-fire in November. Earlier Saturday, Gazans fired four Kassam rockets into Sderot; one scored a direct hit on a home, sending several people into shock. Three terrorist organizations - Islamic Jihad, and Fatah's Aksa Martyrs Brigades - claimed responsibility for the rocket attacks in a joint statement. They said they were carried out to avenge the deaths of three terrorists killed by border police in Jenin earlier in the day. In the Jenin incident, an undercover Border Police unit killed three known terrorists belonging to the Aksa Martyrs Brigades who were driving in a car. Later in the evening, a Palestinian teenager was killed in Jenin when security forces raided her house in search of her brother, a wanted terrorist. Several hours earlier, gunfights broke out between troops and Palestinians in a village near Jenin. PA policeman Muhammad Said Abed, 22, was killed in the clashes. Separately, a full closure was imposed on the West Bank and the Gaza Strip starting at midnight, to remain in effect until after Independence Day on Monday. IDF officials said its liaison office would allow Palestinians to enter Israel in cases deemed "exceptional." AP contributed to this report.