A 16-year-old boy was critically injured Thursday afternoon when Arab terrorists opened fire at a school bus traveling in southern Israel near the Nahal Oz crossing. A second person -- the driver of the bus and the only other person in the vehicle at the time -- sustained shrapnel wounds in the leg. Others in the area suffered shock and severe anxiety. The bus, which was struck from behind, was hit at the Sa'ad junction, just outside Kibbutz Sa'ad in the Sha'ar HaNegev Regional Council district. The front windows of the bus were shattered as well. Magen Dovid Adom medics raced to the scene and stabilized the boy's condition while receiving mortar fire before he was airlifted to Soroka Medical Center in Be'er Sheva. The boy has been admitted to the Trauma Unit. with head injuries, according to hospital officials. The wounded driver was also rushed to the hospital. Although police initially identified the weapon as a medium anti-tank missile, other reports indicated that it may have been a mortar attack. A barrage of mortar shells and rockets continued to be fired at the area following the attack. One exploded next to a house in the Eshkol region. Miraculously, no one was physically injured although the house was badly damaged. At least 16 projectiles had been fired at Israel's southern region by 5:00 p.m. local time. Residents of local Gaza Belt area communities were ordered by IDF Home Front Command to enter their bomb shelters. Among those ordered into the shelters was Science & Technology Minister Professor Daniel Hershkowitz (Jewish Home), who was touring the south at the time. MDA has raised its alert level to "Level B," one stage short of the highest level and roads into the area have been sealed off by the IDF in order to prevent civilians from entering the area and accidentally exposing themselves to rocket and mortar fire. No group has yet claimed responsibility for the attacks. An emergency hotline for the Sha'ar HaNegev Regional Council has been opened. The number to call is: 08-680-6450. Defense Minister Ehud Barak ordered the IDF high command to respond to the attack "immediately" and to use "all necessary means." He added that he holds the Hamas terrorist organization "complete responsible for all attacks emanating from Gaza," which the group rules with an iron fist. Within an hour, an Israel Air Force attack helicopter aimed machine gun fire at a target east of Gaza City for the first time since Israel's counter terrorism war against Hamas in the winter of 2008-2009, Operation Cast Lead. According to Gaza sources, one man was killed and five other people were injured. Hamas sources alleged that a child was among the wounded. The missile and mortar fire on southern Israel came in the wake of overnight air strikes by IDF warplanes on three terrorist smuggling tunnels in southern Gaza, and an infiltration tunnel in northern Gaza. The IDF confirmed direct hits on all targets and said that all planes returned safely to base. Yesterday, a senior Hamas military commander was killed in a an airstrike that destroyed a car in Port Sudan. Sudan emphatically blamed Israel for the attack. Israeli officials had no comment. Prayers have been requested for Daniel Aryeh ben Tamar, the young man wounded in the attack .