The IDF stepped up its offensive against Islamic Jihad rocket squads in the Gaza Strip on Thursday, killing nine Palestinians in a series of ground and air strikes after a long-range Katyusha rocket struck northern Ashkelon for the first time. No one was wounded by the Katyusha attack, which was not the first time that Ashkelon has been hit by Gazan rockets. In July, a Kassam rocket hit the center of Ashkelon. Until then, rockets had only struck the industrial zone on the city's southern outskirts. The Popular Front for the Liberation of Palestine - General Command, the Popular Front for the Liberation of Palestine, the Popular Resistance Committees and Islamic Jihad all took credit for the attack in separate statements issued in the Gaza Strip and Syria. A senior PA representative accused Iran and Syria of working to torpedo US President George W. Bush's visit to the region next week. He pointed out that all four groups that claimed responsibility for the firing of the Katyusha were closely affiliated with Syria and Iran. "The instructions for firing the Katyusha rocket came from Damascus and Teheran," he said. "The timing of the rocket attack is no coincidence and is mainly aimed at disrupting Bush's visit." The 122mm Grad-type Katyusha rocket flew just over 16 kilometers, the farthest a Palestinian rocket has reached to date. Islamic Jihad is believed to have a number of old Grad-type Katyushas with a maximum range of 25 km. Also during the day, three Kassam rockets and 10 mortar shells were fired at the western Negev, including one rocket that hit the backyard of a home in Sderot. A senior official in the Prime Minister's Office characterized the rocket attack on Ashkelon as "very problematic" and "a strategic threat," and said it showed once again the urgency of stopping the arms smuggling from Sinai into the Gaza Strip. "We are concerned that the types of weapons coming into Gaza are giving them new strategic potential," the official said. "This was not the first rocket of this type to be fired on Israel, but we are concerned that unless decisive action is taken there could be more of this." "If we see ongoing smuggling into Gaza of munitions and weaponry, then this a strategic threat for a quarter of a million people in the South who are within the range of the rockets," he said. The official said the government could not sit "idly by," and warned - without mentioning anything about plans for stepped up military action as a result of the rocket attack - that the "continued flow of weaponry and armaments into Gaza from Sinai is an escalatory phenomenon and could lead to a further destabilization in the south." While saying that there was no sense of "crisis" as a result of the rocket attack, the official said it was clear that the current level of weapons smuggling can not go on, and that "actions have to be taken." He did not elaborate. In response to the Katyusha attack IAF jets bombed three buildings in the Gaza Strip, including a weapons storehouse in Gaza City and a Hamas military headquarters in the south. The fighting in Gaza began just after midnight Wednesday when Golani infantry backed by tanks and air support swept into the southern Gaza Strip near Khan Yunis. During the ensuing clashes, troops shot and killed two Hamas operatives and wounded seven. Later Thursday, an IDF tank shell struck a home in Khan Yunis, killing a top Islamic Jihad commander, his mother and sister. The IDF said that gunmen inside the house had fired at troops operating nearby. The dead were identified as 28-year-old Sami Hamden, his 50-year-old mother and his sister Osama, 19. Palestinian medical officials said that six people were wounded in the strike. Dr. Moaiya Hassanain of the Palestinian Health Ministry in Gaza said there were five dead and 21 wounded, among them five in critical condition, from both of Thursday's incidents. On Wednesday, six Palestinians were killed in clashes with the IDF and a senior commander of the Popular Resistance Committees was wounded. Islamic Jihad and the Popular Resistance Committees, which are responsible for most of the Kassam rocket fire, pledged to strike farther into Israel. "We are going to launch more strikes in the depth of the entity," they said in a joint statement. Also Thursday, Ynet reported that a National Security Council report warned that rocket attacks on Israel are liable to increase as a result of both technological improvements in the projectiles, which will bring more Israel communities into range, and increased participation of Hamas in the launches. According to the report, the terrorist organizations in Gaza already have rockets that can reach past Ashkelon and to Ofakim. The report also said that Israel has yet to formulate an adequate response to the rockets, which it described as the terrorist organizations' primary weapon against Israel. The report said there have been attempts to transfer rockets and technology to the West Bank, and that the organizations were being assisted by Iran and Syria. In the West Bank on Thursday, the IDF raided Nablus with at least 50 jeeps, in its largest operation there in about four months. During the operation, clashes broke out between locals and troops and around 20 Palestinians were wounded, including an infant who Palestinian medical officials said was in serious condition. In a raid on a village north of Nablus, troops discovered a large weapons cache including a number of ready-made bombs. AP contributed to this report.