An anti-tank missile fired from the Gaza Strip struck a school bus in the Negev on Thursday, critically wounding a 16-year-old boy and setting off a fierce round of clashes between the IDF and Palestinian terrorists.The missile, which was fired by Hamas, hit the bus moments after most of the children got off, while it was driving near Kibbutz Saad, about 2.5 km. from Gaza. Only two people were on the bus when it was hit – the driver, who was lightly injured, and the boy, who was en route to visit his grandmother. The bus driver is a friend of the family.RELATED:Barak orders IDF to respond speedily to Negev attackHamas, Gaza groups: Israel's crimes won't go unpunishedImmediately after the attack, Palestinians fired more than 45 mortar shells and Katyusha and Kassam rockets into Israel.One of the Grad-model Katyusha rockets was intercepted by the Iron Dome counter-rocket defense system deployed south of Ashkelon, proving its capabilities in combat for the first time.IDF officers said that the attack – the first time an anti-tank missile was fired deep into Israel, and, officers believe, deliberately targeting the school bus – “crossed all red lines” and that Hamas would pay dearly.Options under consideration include a renewal of targeted killings in the Gaza Strip – although it is thought that could move Hamas to launch rockets into the Tel Aviv area.The IDF had intelligence about the attack, which was carried out in retaliation for the bombing of a car last Saturday in southern Gaza carrying senior Hamas operatives planning attacks against Israelis visiting Sinai. The IDF believes that Hamas wanted to attack a military target but, after it did not find one, decided to fire at the bus. “We will not tolerate this attack,” Defense Minister Ehud Barak said during a visit to Gaza Division headquarters.“Our response will continue as long as necessary to make it clear to the other side that these types of attacks will not be tolerated. We hold Hamas responsible for everything that comes out of Gaza and expect that Hamas understands what is permitted and what is forbidden.”The 16-year-old boy was evacuated to Soroka University Hospital in Beersheba after extensive treatment at the surgery for wounds to the head and other parts of the body. He was listed in critical condition.The bus driver was lightly wounded in the leg.The bus had dropped off the rest of its young passengers in communities around the Sha’ar Hanegev Regional Council, and was making its way to its last destination.IDF sources said that the bus was hit by a guided anti-tank missile.Hamas and Islamic Jihad are believed to have a significant arsenal of Russian-made anti-tank missiles like the Kornet and Faggot that have a range of several kilometers.Following the attack, Homeland Security Minister Matan Vilna’i ordered the Defense Ministry to send three armored buses to the Shar Hanegev Regional Council, to be used to take children to and from schools in the western Negev. Israel Air Force attack helicopters and IDF tanks struck back at a number of targets throughout the Strip, hitting a Hamas military compound in Gaza City for the first time since Operation Cast Lead over two years ago.Three people were reportedly killed and at least eight people, including a four-year-old girl, were wounded in the strikes, according to Palestinian medics.Children were ordered to stay in schools and kindergartens with their teachers during the ongoing mortar and rocket fire.A mortar shell struck a home in the Eshkol Regional Council. The building sustained damage, but police said no injuries were reported.Police sealed off roads in the area due to the threat of additional fire. Civilians in the area were asked to remain in their homes.Police also sealed off roads around Netivot, and pupils were stranded at schools with their teachers after local authorities said it was dangerous to go outside.“All residents must remain in protected areas. We have opened a special control room, and teams of psychologists and social workers have arrived, escorted by IDF soldiers, to provide assistance,” Sha’ar Hanegev Regional spokeswoman Michal Shaban- Kotzer told The Jerusalem Post.Southern district police spokeswoman Sarit Phillipson said a beefed-up police presence and police checkpoints would be maintained throughout the western Negev into Thursday night.