At least eight 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. local time in the country's south, in the southern suburbs of Beirut known as Dahieh and the eastern Bekaa Valley — all Hezbollah strongholds.

They lasted for around an hour, with Reuters witnesses and residents of Dahiyeh saying they could still hear explosions at 4:30 p.m.

According to security sources and footage reviewed by Reuters, some of the detonations took place after the pagers rang, causing the fighter to put their hands on them or bring them up to their faces to check the screen.

WATCH | Several killed, thousands wounded by blasts: 

Hezbollah members among hundreds wounded when pagers explode in Lebanon

At least three people were killed and more than 1,000 others, including Hezbollah fighters and medics, were wounded when their pagers exploded across Lebanon, security sources told Reuters.

How big were the explosions?

The blasts were relatively contained, according to footage reviewed by Reuters. In two separate clips from the CCTV footage of supermarkets, the blasts appeared to only wound the person wearing the pager or closest to it.

Footage shot at hospitals and shared on social media appeared to show individuals with injuries of varying degrees, including to the face, missing fingers, and gaping wounds at the hip where the pager was likely worn.

The blasts did not appear to cause major damage or start any fires.

What type of pager exploded?

Images of the destroyed pagers analyzed by Reuters showed a format and stickers on the back consistent with those made by Gold Apollo, a Taiwan-based pager manufacturer.

The firm did not immediately reply to questions from Reuters. Hezbollah did not reply to questions from Reuters on the make of the pagers.

Hezbollah fighters had begun using pagers as a low-tech means to try and avoid Israeli tracking of their locations, two sources familiar with the group's operations told Reuters earlier this year.

Three security sources told Reuters that the pagers that detonated were the latest model brought in by Hezbollah in recent months.

What caused the pagers to explode?

Hezbollah said it was carrying out a "security and scientific investigation" into the cause of the blasts.

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

Experts were mystified by the explosions, but several who spoke to Reuters said they doubted the battery alone would have been enough to cause the blasts.

Paul Christensen, an expert in lithium-ion battery safety at Newcastle University, said the level of damage caused by the explosions seemed inconsistent with known cases of such batteries failing in the past.

"What we're talking about is a relatively small battery bursting into flames. We're not talking of a fatal explosion here. I'd need to know more about the energy density of the batteries, but my intuition is telling me that it's highly unlikely."

SMEX, a Lebanese digital rights organization, told Reuters that Israel could have exploited a weakness in the device to cause it to explode. It said the pagers could also have been intercepted before reaching Hezbollah and either tampered with electronically or implanted with an explosive device.

Israel has not claimed responsibility for or commented on the explosions.

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

What have the authorities said about the blasts?

Lebanon's foreign ministry called the explosions an "Israeli cyber attack," but did not provide details on how it had reached that conclusion.

Lebanon's information minister said the attack was an assault on Lebanon's sovereignty.

Israel's military declined to comment to Reuters questions on the pager blasts.