A midair collision between an Army helicopter and a jetliner killed all 67 people aboard the two aircraft, officials said Thursday, as they scrutinized the actions of the military pilot in the country’s deadliest aviation disaster in almost a quarter century.

Israeli strikes on Monday killed more than 270 Lebanese in the deadliest barrage since the 2006 Israel-Hezbollah war as the Israeli military warned residents in southern and eastern Lebanon to evacuate their homes ahead of a widening air campaign against Hezbollah.