Escalating the conflict in Gaza, the Israeli air force fired heavy artillery strikes in the region on Friday, allegedly killing two Palestinian militants and three civilians. The strikes were an act of retaliation after Hamas fired missiles at an Israeli school bus Thursday, critically wounding a 16-year-old boy. Each attack has beckoned another from the warring groups with tensions building for weeks. Hamas leaders claimed the school bus attack was in retaliation for Israel's attempt to kill three Hamas militants last weekend. The Israeli army said in a statement Friday that it had "identified two terrorist squads" from Hamas and struck at them, but Palestinians maintain that a majority of those killed were civilians. "They target children, we target terrorists," said Israeli Education Minister Gideon Saar. In regard to the deaths of civilians in Gaza, Saar said, "We do our utmost to minimize such casualties."