An explosive and ammunition expert believes that Israel was behind what he called a highly sophisticated and unprecedented attack on Hezbollah fighters in Lebanon when their pagers detonated.

Local sources report that Israel hacked the devices, causing the explosions – Watch video of the explosion moments

Just as crowds had gathered to mourn some of those killed in Tuesday’s wave of pager-bomb attacks, an explosion sparked chaos in Dahiya, Hezbollah’s stronghold in southern Beirut. A video captured the blast,

Just as crowds had gathered to mourn some of those killed in Tuesday’s wave of pager-bomb attacks, an explosion sparked chaos in Dahiya, Hezbollah’s stronghold in southern Beirut. A video captured the blast, showing a man lying on the ground and panicked people, some screaming, running away.

The two waves of explosions rocked Syria and Lebanon, killing at least 21 people and wounding thousands more, with concerns being raised over another conflict on Israel's northern border

At least nine people were killed and nearly 3,000 people wounded across Lebanon on Tuesday afternoon when hundreds of pagers used by Hezbollah and others almost simultaneously exploded. Hezbollah has blamed Israel, where officials and the military have made no comment.

At least three people are reported to have died in the latest blasts, a day after thousands of pagers exploded across Lebanon.

Hezbollah claims the attack was carried out by Israeli forces and vows to respond. Israel has declined to comment

Stephen Zunes, a professor of politics at University of San Francisco joins KTVU"s Alex Savidge to discuss the latest developments in Lebanon.