Thousands injured in deadly pager explosions across Lebanon and Syria | Key facts

Sophisticated, remote attack on Hezbollah members in Lebanon and Syria kills nine, wounds thousands, sparking theories of Israeli involvement.

In what appears to be a sophisticated, remote attack, pagers used by hundreds of members of Hezbollah exploded almost simultaneously in Lebanon and Syria Tuesday, killing at least nine people — including an 8-year-old girl — and wounding thousands more.

The Iran-backed militant group blamed Israel for the deadly explosions, which targeted an extraordinary breadth of people and showed signs of being a long-planned operation. How the attack was executed is largely uncertain and investigators have not immediately said how the pagers were detonated. The Israeli military has declined to comment.

Hezbollah leader Hassan Nasrallah previously warned the group’s members not to carry cellphones, saying they could be used by Israel to track the group's movements. As a result, the organization uses pagers to communicate.

A Hezbollah official told The Associated Press the exploded devices were from a new brand the group had not used before. The official, who spoke on condition of anonymity because he was not authorized to talk to the press, did not identify the brand name or supplier.

Nicholas Reese, adjunct instructor at the Center for Global Affairs in New York University’s School of Professional Studies, explains smart phones carry a higher risk for intercepted communications in contrast to the more simple technology of pagers.

This type of attack will also force Hezbollah to change their communication strategies, said Reese, who previously worked as an intelligence officer, adding that survivors of Tuesday's explosions are likely to throw away "not just their pagers, but their phones, and leaving their tablets or any other electronic devices.”

With little disclosed from investigators so far, multiple theories have emerged Tuesday around how the attack might have been carried out. Several experts who spoke with The Associated Press suggest that the explosions were most likely the result of supply-chain interference.