Hamas vowed on Sunday to avenge the death of two of its members who were killed in Kalkilya by security forces loyal to Palestinian Authority President Mahmoud Abbas. The two, Muhammad Samman and Ahmed Yassin, were killed in a pre-dawn raid carried out by Abbas's security forces on a building where they were hiding. Three policemen and the owner of the building, Abdel Nasser Basha, were also killed in the raid, which was described as one of the bloodiest intra-Palestinian incidents in the West Bank in recent years. The policemen killed in the raid were identified as Shaher Hanineh, Abdel Rahman Yassin and Hussam Abu al-Rakh. The two Hamas fugitives were commanders of Hamas's armed wing, Izaddin al-Kassam, in the northern West Bank. They were also wanted by Israel for their involvement in a series of terror attacks over the past few years. Abbas praised his security forces for their role in killing the two men, saying the PA would use an iron fist against anyone who tampers with the interests of the Palestinians. He accused Hamas of seeking to create a "state of confusion and instability" in the PA territories. The two Hamas men were killed after a six-hour standoff with dozens of Palestinian policemen who had urged them, through loudspeakers and family members, to surrender, but to no avail. Hamas officials claimed that IDF soldiers had participated in the raid. However, a spokesman for the Palestinian security forces in the West Bank strongly denied the involvement of any Israeli soldier in the confrontation with Hamas. Another senior member of Izaddin al-Kassam, Abdel Majid Dudeen, was killed by IDF troops near Hebron less than 48 hours before the Kalkilya incident. The death of the three senior Hamas operatives is seen as a severe blow to Hamas's extremely secretive military infrastructure and a significant victory for Abbas's US-backed security forces in foiling Hamas's efforts to extend its control to the West Bank. A fatwa (Islamic religious decree) issued by a Hamas official in the Gaza Strip, Marwan Abu Ras, ruled that any member of Abbas's security forces who kills a Palestinian gunman should be ostracized and treated as a "traitor." Abu Ras, who also serves as chairman of the Palestinian Religious Scholars' Association, also ruled that any Palestinian who is killed by Abbas's security forces should be viewed as if he had been killed by the IDF and hence elevated to the status of shahid (martyr). He said the raid in Kalkilya was directly linked to the killing of Dudeen, who had been wanted for nearly two decades. "Abbas's forces completed the job the Israeli enemy began in the Hebron area," he said. "Abbas's forces carried out the mission promptly and in full coordination with the Israelis." The armed wing of Hamas said its men would pursue and punish those responsible for the Kalkilya killings. Abu Obaidah, a spokesman for Izaddin al-Kassam, told reporters in the Gaza Strip that Abbas and his security forces were directly responsible for the "cowardly attack" and would bear the consequences. Abu Obaidah said that Hamas fugitives in the West Bank were entitled to resist any attempt to arrest them by the "pro-Zionist Abbas security forces." He added that Hamas does not distinguish between the occupation and a "collaborator" who tries to carry out a mission on its behalf. "We call on all our people to stand up to this group of Palestinians that has sold itself to the devil," he said, referring to Abbas loyalists. "We call on our people in the West Bank to urge their sons who serve in these forces, which are controlled by [US security coordinator] Keith Dayton, to quit immediately." Abu Obaidah noted that Samman, one of the Hamas men killed in Kalkilya, had been on Israel's list of wanted men for the past six years, during which time he managed to evade several attempts to arrest or kill him. Hamas spokesman Sami Abu Zuhri said that the Kalkilya "crime" would "poison" efforts to achieve reconciliation between his movement and Fatah. Hamas legislator Salah Bardaweel said that his movement was now considering boycotting the next round of talks with Fatah, slated for next week, in protest against the Kalkilya incident. Bardaweel accused Abbas and his prime minister, Salaam Fayad, of ordering their security forces to eliminate Hamas members in the West Bank to appease Israel. "We are considering suspending our participation in the Cairo dialogue [with Fatah] in protest against Abbas's crimes," he said. "We call on the Egyptians sponsors to force Abbas to stop the arrests and assassinations." Hamas said that Abbas's forces had also arrested 15 of its supporters in Kalkilya and other parts of the West Bank over the previous 24 hours. Fatah, on the other hand, announced that Hamas militiamen rounded up 16 members of the Aksa Martyrs Brigades in the Gaza Strip. Adnan Damiri, spokesman for the PA security forces, accused Hamas of targeting Palestinian policemen to serve the agendas of "external powers." "Hamas has instructed its members to destroy the Palestinian Authority and its security forces," he charged. He said the two men who were killed in Kalkilya had stored weapons in mosques and residential areas in the city, endangering the lives of civilians.