Tel Aviv, Dec 17 : The Israel Defense Forces (IDF) said on Sunday that it has raided a building near a United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) school and found three tunnel shafts in the area of the school. The IDF said in a statement that the 646th Brigade of the troops conducted the raids and found rocket building materials also present in the building. The IDF in the statement said that it carried out strikes against nearly 200 Hamas sites in the Gaza Strip till Saturday and added that Paratroopers Brigade raided several apartments used by the Hamas in Gaza City's Shejaiya, and found firearms, explosive devices and other military equipment. It also added that the troops discovered a 15-metre-long tunnel, which was later destroyed in an airstrike. In southern Gaza, the IDF says the Commando Brigade directed an airstrike on a Hamas weapons depot at the home of an operative. Since the IDF invaded the Gaza Strip from October 27, the Israeli military has lost 121 soldiers while more than 6,000 Hamas operatives were killed. /IANS