What we know about the deadly pager blasts in Lebanon

At least nine people were killed and nearly 3,000 wounded when pagers used by Hezbollah members – including fighters and medics – detonated simultaneously across Lebanon.

Here's what we know so far about the pager blasts.

When and where did the blasts take place?

The detonations started around 3:30 p.m. in the southern suburbs of Beirut known as Dahiyeh and the eastern Bekaa valley – strongholds of the anti-Israel militant group Hezbollah. The blasts lasted around an hour.

According to security sources and footage, some of the detonations took place after the pagers went off, causing the fighters to put their hands on them or bring them up to their faces to check the screens.

The blasts were relatively contained. In two separate clips from closed-circuit video of supermarkets, the blasts appeared only to wound the person wearing the pager or closest to it.

Video from hospitals and shared on social media appeared to show individuals with injuries to their faces, missing fingers and gaping wounds at the hip where the pager was likely worn. The blasts did not appear to cause major damage to buildings or start any fires.

Who is responsible for the explosion?

Citing a senior Lebanese security source, Reuters reported that explosives inside the pagers were planted by Israel's Mossad spy agency months before Tuesday's detonations to target Hezbollah fighters as they have been using pagers as a low-tech means of communication in an attempt to evade Israeli location-tracking.

The senior security source said the group had ordered 5,000 beepers made by Taiwan-based Gold Apollo, which several sources say were brought into the country in the spring. But the senior Lebanese source said the devices had been modified by Israel's spy service "at the production level."

"The Mossad injected a board inside of the device that has explosive material... It's very hard to detect it through any means. Even with any device or scanner," the source said.

The source said 3,000 of the pagers exploded when a coded message was sent to them, simultaneously activating the explosives.

Gold Apollo's founder said the company did not make the pagers used in the explosions in Lebanon. They were manufactured by a company in Europe that had the right to use the Taiwan firm's brand.

What caused the pagers to explode?

Iran-backed Hezbollah said it was carrying out a "security and scientific investigation" into the causes of the blasts and said Israel would receive "its fair punishment."

Diplomatic and security sources speculated that the explosions could have been caused by the devices' batteries detonating, possibly through overheating.

But others said that Israel might have infiltrated the supply chain for Hezbollah's pagers.

The New York Times reported that Israel hid explosive material within a new batch of the pagers before they were imported to Lebanon, citing American and other officials briefed on the operation.

Several experts who spoke with Reuters said they doubted the battery alone would have been enough to cause the blasts.

Paul Christensen, an expert on lithium-ion battery safety at Newcastle University in Britain, said the damage seemed inconsistent with past cases of such batteries failing.

"What we're talking about is a relatively small battery bursting into flames. We're not talking of a fatal explosion here ... my intuition is telling me that it's highly unlikely," he said.

Another reason to doubt the explosions were caused by overheating batteries is that typically only a fully charged battery can catch fire or explode, said Ofodike Ezekoye, a mechanical engineering professor from University of Texas at Austin.

"Below 50 percent (charge) ... it will generate gases and vapor, but no fires or explosions. It is highly unlikely that everyone whose pager failed had a fully charged battery," he said.

Israeli intelligence forces have previously placed explosives in personal phones to target enemies, according to the 2018 book "Rise and Kill First." Hackers have also demonstrated the ability to inject malicious code into personal devices, causing them to overheat and explode in some instances.

What are the reactions?

Lebanon's foreign ministry called the explosions an "Israeli cyberattack." Lebanon's information minister said the attack was an assault on the country's sovereignty.

The U.S. State Department said Washington is gathering information about the incident. The Pentagon said there is no change in U.S. force posture in the Middle East in the wake of the incident.

Israel and Hezbollah have exchanged cross-border fire since the start of the Israel-Hamas conflict in Gaza last October. The pager explosions further escalated their tensions.

Matthew Levitt, former deputy director of the U.S. Treasury's intelligence office and author of a book on Hezbollah, said the pager explosions could disrupt its operations for some time.

Jonathan Panikoff, the U.S. government's former deputy national intelligence officer on the Middle East, said Hezbollah might downplay its "biggest counter-intelligence failure in decades" but rising tensions could eventually erupt into full-scale war if diplomacy continues to fall short.

(With input from Reuters)