Israel called on foreign citizens and journalists to leave the Gaza Strip ahead of an increase in IDF operations in the area. According to a Channel 2 report, many journalists and foreigners have already left the Gaza Strip since Wednesday evening. Also early Thursday, the IAF attacked a building belonging to the Fatah in the southern Gaza Strip. According to the IDF Spokesperson, the building was used for terror operations. Earlier, the IDF struck at access routes in the area in order to prevent kidnapped IDF soldier Cpl. Gilad Shalit's kidnappers from moving him from place to place. IDF forces also shelled Palestinian Authority police positions on the northern Gaza beach early Thursday, Palestinian witnesses said, killing one Hamas operative and a PA policeman and wounding six officers from the PA's coastal police, three seriously. Hospital officials identified the dead Hamas man as Hussam Hijazi, 24. Palestinians said Hamas operatives were in the area at the time. Palestinian security officials said the target was apparently a coastal police station. It was unclear where the shells came from. Palestinian officials said either IDF navy gunboats or IDF tanks fired the shells. The IDF, for its part, said it did not open fire on the area. [For a Jerusalem Online video of events click here] The IDF strenuously denied Palestinian reports early Thursday that IDF tanks and armored personnel carriers were advancing through Beit Lahiya and Beit Hanoun in the northern Gaza Strip. According to Israel Radio, the IDF did confirm that troops were taking positions in northern Gaza, but would not specify their locations. According to media reports, there were fierce gun battles taking place between troops and Palestinians in northern Gaza near the former northern Gaza settlement Nisanit early Thursday. The IDF said that all operations in northern Gaza were part of the ongoing Operation Summer Rains intended to retrieve Cpl. Shalit. Conflicting initial reports gave different causes for an explosion that struck a car carrying reporters from the Al-Jazeera satellite TV channel on Wednesday night in Beit Lahiya. According to witnesses, there were apparently some injuries, and ambulances were on the way to the scene. According to the latest reports, the incident was apparently caused when Palestinian gunmen mistook the Al-Jazeera crew for undercover IDF troops on an arrest operation and immediately opened fire on them. A Kassam rocket landed in Ashkelon's southern Shimshon neighborhood shortly after 9:00 p.m. Wednesday, only a day after a Kassam rocket landed within the Ashkelon city limits for the first time. Five people, including two children, suffered from shock and were evacuated to Barzilai Hospital. No damage was reported. [For a Jerusalem Online video of events click here] Hamas' military wing claimed both the Kassam attack on Ashkelon as well as a Kassam that was fired at the western Negev and landed in an open field, sparking a fire. No one was wounded in any of the attacks. Defense Minister Amir Peretz said Wednesday that there was "no difference between Kassams fired at Ashkelon and Kassams fired at Sderot." "We are more determined than ever to strike Hamas and the terror infrastructure," the defense minister emphasized. Late Tuesday night, following the Kassam attack, the IAF struck back at Palestinian terrorists by firing missiles at the Hamas-run Interior Ministry in the southern Gaza Strip and a school in northern Gaza. By day it's a school, an IDF spokesman said, and by night it's a meeting place for terrorists. The strike against the Interior Ministry was the second time the building was targeted in the past week. Rescue workers said five people were wounded. The Kassam rocket that hit Ashkelon traversed a record range of 12 kilometers, sending the city's 120,000 residents into a state of fear that their city would be bombarded by rockets like Sderot has since the disengagement last summer. Prime Minister Ehud Olmert termed the Kassam attack a "grave escalation" for which Hamas is responsible and for which there will be far-reaching ramifications. Olmert's comments came at the annual July 4th celebration held at the residency of the US ambassador to Israel in Herzliya Pituach. "Tonight a grave escalation took place when a Kassam landed in a school in our southern town. This is a peerless and grave escalation in the terrorist war for which Hamas, which is in control of the Palestinian government, is responsible," Olmert said. He said there will be significant ramifications for this "criminal attempt" to strike at Israeli citizens. He said Hamas would be the first to be hit. In response to the attack, Defense Minister Amir Peretz ordered the IDF to step up the speed and intensity of Operation Summer Rains in the Gaza Strip, launched last Wednesday in an effort to retrieve Cpl. Gilad Shalit. "We intend to achieve the goals of our operations in Gaza," Peretz said, referring to stopping the Kassam rocket fire as well as retrieving the kidnapped IDF soldier. No one was wounded by the rocket, which landed in a playground of a school in the heart of the Ashkelon residential area. Children playing soccer outside the ORT-Ronson High School on Rehov Ben Zvi were thrown back by the force of the explosion, witnesses reported, but were unharmed. The school suffered some damage. Earlier in the day, four rockets landed in the western Negev without causing any injuries. Security officials described the Kassam as "upgraded," although featuring only one engine. Southern Police chief Cmdr. Uri Bar-Lev said security forces had seen this type of rocket in the past and called on the residents of Ashkelon to remain calm and to carry on their lives as usual. Hamas' military wing, Izzadin al-Kassam, claimed responsibility for the attack while claiming that the rocket had been upgraded to achieve a range of over 15 kilometers. Security officials said the rocket was fired from an open area between the former northern Gaza settlements of Nisanit and Dugit. In the past, Kassams have landed in Ashkelon's periphery, particularly in the industrial zone. But in contrast to Sderot, Ashkelon is not equipped with the Red Dawn early warning system which alerts residents of an incoming rocket. Spokeswoman for Ashkelon Municipality said that Mayor Roni Mahetzri was encouraging residents to go about their daily lives and vowed that terrorism would not win. Meanwhile Tuesday, the IDF stepped up its offensive on the Gaza Strip despite the expiration of an ultimatum issued by the kidnappers of Shalit, abducted from his military outpost outside southern Gaza last Sunday. On Monday, several tank squads, bulldozers and infantry companies took up positions in northern Gaza opposite Beit Hanoun. On Tuesday, additional forces were sent into Gaza establishing a battalion-level presence in northern Gaza. AP contributed to this report.