HARET HREIK, Lebanon — Hezbollah on Wednesday confirmed the killing of one of its senior commanders in an Israeli airstrike a day earlier, calling it a “major crime” without saying how it would respond, as Lebanon and the wider region waited on edge.

       The confirmation of the death of the commander, Fuad Shukr, was delayed as rescue workers searched Wednesday through the rubble of a residential building in Haret Hreik, a heavily populated Beirut suburb, using excavators and drilling machines. Shukr had been on one of the bottom floors, a Hezbollah media officer explained.