Israel was responsible for Tuesday's explosions, a source confirmed to ABC News, in which pagers detonated across Beirut and southern Lebanon. Walkie-talkies exploded on Wednesday. The strikes come after two consecutive days of explosions of pagers and walkie-talkie devices in Lebanon, which left at least 37 people dead.

The explosions of hundreds of electronic devices in an apparent targeting of Hezbollah members in Lebanon suggests a sophisticated attack with months of planning.