Violence marred the cease-fire in the Gaza Strip on Tuesday as Hamas gunmen fired mortar shells into Israel and opened fire on IDF troops who remained inside the Palestinian territory. In the afternoon, IAF aircraft bombed a mortar launcher in the Gaza Strip that had been used hours earlier to fire some eight mortar shells into the Negev. It was the first air strike against Gaza since Israel unilaterally implemented a cease-fire there on Sunday. Earlier in the day, Gaza gunmen fired at IDF patrols in two separate incidents that marked the first violations of the cease-fire Hamas accepted on Sunday after the IDF began withdrawing its forces from Gaza. No one was wounded and no damage was reported in either of the two incidents, which took place near the Kissufim border crossing in central Gaza, and in southern Gaza. IDF troops returned fire following one of the attacks. Defense officials further accused Hamas of stealing some of the humanitarian supplies that had been transferred into the Gaza Strip. The officials said the Hamas leadership had issued orders already on Monday to attack IDF troops who remained in the Gaza Strip. The Israeli forces were expected to pull out of Gaza in the coming days. According to the officials, Hamas likely chose to fire mortars and not rockets, since it predicted that Israel would have a harsher response to a rocket attack on a town or city. They would not say whether Israel was planning a response in addition to the air strike against the launcher. "We will not tolerate attacks and will not be restrained like we used to be," explained one official. Following reports that Palestinian children had been killed by dud IDF shells left in Gaza, the IDF Spokesman said on Monday that Israel had issued a warning to Gaza residents about the presence of dud shells in the Strip. In messages broadcast in the media, the army instructed the Palestinians to notify the Israeli coordination office immediately if a shell were discovered. Meanwhile Tuesday, Lt.-Col. E, commander of an armored battalion, which participated in the IDF's ground offensive in Gaza, told The Jerusalem Post that he was surprised by the relatively light resistance his unit had encountered from Hamas. His battalion participated in the initial ground operation and succeeded in crossing the Gaza Strip and cutting off the North from the South in under five hours. On the way to the Gaza coast, he said, the troops came under Hamas fire only once. "There were different threats from anti-tank missiles, mortar shells and improvised explosive devices," E said. "It appeared, though, that while almost all of the homes were booby-trapped, Hamas did not have a chance to use the IEDs, since we found a bunch of them in a storehouse under a chicken coop."