Two IDF officers and a soldier were killed on Thursday as the IDF penetrated deeper into urban centers in the northern Gaza Strip. In the evening, fierce clashes erupted in the Zeitoun neighborhood of Gaza City between Golani Brigade soldiers and Hamas terrorists. At least 10 gunmen were reported killed. Capt. Omer Rabinovitch, 23, of Arad, was killed in the close-quarter firefights in Zeitoun. Sgt. Amit Robinson, 21, a tank crewman from Kibbutz Magal, south of Baka al-Gharbiya, was killed by a sniper, also in northern Gaza. His parents made aliya from Argentina. Earlier in the day, Maj. Ro'i Rosner of the Kfir Brigade's Haruv Battalion was killed and another soldier was lightly wounded, when a Hamas man fired an anti-tank missile at them as they conducted searches near the Kissufim crossing into the Strip. Nine IDF soldiers have been killed since the start of Operation Cast Lead. In the afternoon, seven soldiers were wounded, one of them seriously, by a mortar shell in the Eshkol region. Gazans reported some two dozen IAF strikes on Thursday. One gunman was killed and 10 were wounded in Gaza City, while an air strike in northern Gaza killed three members of a rocket-launching cell, Palestinian medical officials said. The attack took place about 150 meters from a hospital and wounded 12 bystanders. While the fighting intensified on Thursday, on Wednesday night there were no clashes reported by the soldiers operating inside the Gaza Strip. Some 30 rockets were fired on southern Israel on Thursday. Officials said Hamas was believed to have several dozen long-range Katyusha rockets left in its arsenal, and that the Islamist group was trying to smuggle additional weaponry from Sinai into Gaza through tunnels in Rafah. Nevertheless, defense officials estimated that it would take Hamas "several years" to recover from Operation Cast Lead. The United Nations halted aid deliveries to Gaza after one of its drivers was killed as he was picking up a shipment on Thursday. "The UN is suspending its aid operations in Gaza until we can get safety and security guarantees for our staff," spokesman Chris Gunness said. "We've been coordinating with them [Israeli forces] and yet our staff continue to be hit and killed." The UN has already demanded an investigation into Israel's shelling of a UNWRA school that killed at least 30 people earlier this week. Israel said Hamas men were firing mortar shells at troops from within the school grounds at the time. For a second straight day, Israel suspended its Gaza military operation for three hours to allow in humanitarian supplies. Overnight Wednesday, Ashkelon residents were woken in the middle of the night by an air raid siren. On Thursday, a rocket struck a school's gymnasium in the city, piercing a wall, while another rocket fell in open territory. Three rockets were fired at Sderot, where one person was treated for shock. AP contributed to this report.