A Palestinian boy was killed during clashes between Israeli forces and militants in southeast Gaza on Thursday. A Gaza medical official said that the boy, Ahmed Abu Dagga, 11, was struck in the head by a bullet and died later in a hospital. Hamas, the Islamic militant group that controls Gaza, said he was killed by Israeli fire. Hamas said that its fighters had set off a bomb against an Israeli force that crossed the border into Gaza with tanks and bulldozers. Israeli tanks and helicopter gunships opened fire during the confrontation, residents said. The Israeli military said that soldiers engaged in routine activity along the border came under fire and fired back, and that it was checking on reports of the boy’s death.