The attacks offer a rare window into the inner-workings of Hezbollah — an organization that is notoriously secretive and deeply embedded in Lebanese society.

Hundreds of pagers carried by Hezbollah members blew up nearly simultaneously in an attack that tops a series of covert assassinations and cyber-attacks in the region.

U.N. peacekeepers in Lebanon urged immediate de-escalation as hostilities rumbled on at the Lebanese-Israeli border on Friday, following Israel's most intense airstrikes in nearly a year of conflict with the Iran-backed Hezbollah.

Explosions were reported in southern Lebanon, including the city of Sidon, as well as Beirut's southern suburbs and the Bekaa Valley At least 20 people have been killed and more than 450 wounded by a second wave of explosions from wireless communication devices in Lebanon,

Additional explosions linked to electronic devices caused more deaths and injuries a day after pagers used by Hezbollah exploded, wounding thousands.

The Hezbollah militant group said it is conducting a "security and scientific investigation” into the explosion of pagers across Lebanon on Tuesday.