Hezbollah was reeling Saturday from an Israeli airstrike that killed two of its senior figures and dozens of other people, intensifying fears of all-out war in the Middle East in the wake of the deadly attacks on the group’s communication devices.

Hezbollah said Ibrahim Akil, who helped establish the militant and political group’s elite Radwan Force, and Ahmed Wahbi, who was in charge of Hezbollah’s central training unit, were killed in the strike Friday on a densely populated suburb of the…