Men from the most effective military force in Lebanon bleeding on the street and sprawled out in hospital beds, wounded not on the battlefield, but by devices carried in their pockets and worn on their belts.

These images of carnage — the result of what Lebanese, American and other officials have called an Israeli operation to remotely detonate hundreds of pagers carried by Hezbollah fighters — are a deep humiliation for the group, puncturing its aura as one of the region’s most sophisticated anti-Israel forces.

“This operation is basically Hezbollah’s Oct. 7,” said Mohanad Hage Ali, a senior fellow at the Carnegie Middle East Center in Beirut, comparing the group’s security failures to those that allowed its ally Hamas to strike Israel last year, starting the war in Gaza. “It is a huge slap.”

Israel has not confirmed or denied involvement in the operation, which the Lebanese authorities say killed at least 12 people and injured nearly 2,800. While one young girl was among the dead, many of those targeted appeared to be connected to Hezbollah, their injuries adding physical blows to the psychological one.

“It is a serious attack,” Mr. Hage Ali said, adding that during 11 months of aerial attacks across the Lebanon-Israel border, Hezbollah had lost many leaders and cadres, some in targeted assassinations.

“And now this blow cuts through the rank and file of the organization,” he said. “It is a kind of sword stabbed deep into the organization’s body, and it will take it time to heal from that.”