The Golani Brigade suffered heavy casualties on Monday when three soldiers were killed and another 24 were wounded, including Golani Infantry Brigade Commander Col. Avi Peled, as an errant tank shell hit their position in the northern Gaza Strip. One of the was identified Tuesday morning as Yousef Moadi, 19, from Haifa. He will be laid to rest at 3 p.m. Tuesday in the Druse village of Yirka. According to reports, a force from Golani's 13th Battalion came under heavy mortar fire in Saja'iya and entered a nearby home for cover. Mistaking the force for Hamas, an IDF tank fired at the home. A shell hit the building which collapsed on the force. Three soldiers were killed and of the 24 wounded, one was in critical condition and another three were in serious condition. The other 20 casualties, including Peled and battalion commander Lt.-Col. Oren Cohen, were lightly to moderately wounded. The fighting lasted several hours as IDF artillery pounded the area and helicopters evacuated the wounded. The clashes marked the first time the IDF extended its ground operation into a densely populated area. Meanwhile, another 12 IDF soldiers were wounded throughout the day in exchanges of fire with Hamas gunmen in the northern Gaza Strip. They were evacuated for medical treatment. In an operation early Monday morning, troops reported that Hamas gunmen tried to kidnap a soldier by pulling him into a tunnel. The soldier managed to free himself. Throughout the day the IDF encountered significant resistance in the northern Gaza Strip, killing close to 100 Palestinians in a series of close-range gun battles. Another 80 were captured and sent for interrogation. One Palestinian was taken to Soroka Hospital in Beersheba under heavy security. Despite the fierce fighting, and with diplomatic activity beginning to gain steam, defense officials predicted Monday that Operation Cast Lead would be over by the end of the week. "If everything goes as planned the operation could be over in the next 72 hours," a senior officer said. While the fighting continued, a top officer said that the forces in Gaza were prepared, if necessary, to enter urban and built-up areas. "This is what the troops have trained for and are designated to do - to fight in densely-populated areas," the officer said. Over the past year, all of the units that have been deployed in Gaza have undergone training at the Ground Forces Command's Urban Training Center near Tze'elim, which has a mock Palestinian city used to train forces to fight in populated areas. "We built models for them of places inside Gaza," the officer said. "There are places that replicate city outskirts, the casbah marketplaces and overpopulated refugee camps." Meanwhile, Defense Minister Ehud Barak said that Gaza was partially cut off. "Hamas has been hit hard, but we have not yet reached the objective that we set for ourselves and therefore the operation is continuing," he added. After reaching their targets early Monday morning, the units began taking up positions inside homes and throughout nearby fields across the northern Gaza Strip. Before moving to another home or target, the IDF operated various surveillance systems, as well as heavy firepower to ensure that it was safe to move in the open. Forty weapons-smuggling tunnels in the Philadelphi Corridor were bombed on Monday and defense officials said that Hamas was too scared to use the tunnels to smuggle further weaponry. Overnight Sunday, the IAF attacked more than 30 Gaza targets, including an underground Hamas bunker, weapons caches and sites from which Grad rockets were fired at Ashkelon. Palestinian officials reported Monday that a family of seven was killed overnight Sunday in IDF shelling. According to the report, five children and their parents died when a shell fired by the navy hit their home in the Shati refugee camp in Gaza City. In two incidents in Gaza City's Zeitun neighborhood, three children were said to have been killed in an IDF strike and a man and his granddaughter were reportedly killed by gunfire in their home. The IDF said it was looking into the reports. But army spokeswoman Maj. Avital Leibovich said that if civilians were killed, Hamas was to blame because it operated within civilian areas. "If Hamas chooses to use those civilians as human shields, then Hamas should be accountable," she said. "Civilians will probably continue to get killed, unfortunately, because Hamas put them in the front line of fire." Jerusalem Post staff and AP contributed to this report.