Hundreds of pagers belonging to the Lebanese armed group Hezbollah exploded simultaneously throughout Lebanon.

At the time of publication, at least nine people were killed and 2,750 injured, according to security services and the Lebanese health minister.

Pagers are small communication devices that were commonly used before cell phones became widely available.

The devices display a short text message to the user, which is transmitted by telephone via a central operator.

Unlike mobile phones, pagers work with radio waves. The operator sends a message not over the Internet, but over a radio frequency specifically designed for the recipient’s device.

It is believed that the basic technology used in pagers and their reliance on physical hardware make them harder to monitor, making them popular with groups like Hezbollah, for whom mobility and security are of paramount importance.

What happened?

The series of explosions began around 4:45 p.m. and lasted about an hour.

The number of victims has yet to be confirmed.

An eight-year-old girl was also confirmed to be among the dead.

Mohammad Mahdi Ammar, the son of Hezbollah MP Ali Ammar, was also reportedly killed.

Hezbollah confirmed that two of its fighters had been killed.

Lebanese Health Minister Firass Abiad told Al Jazeera: “About 2,750 people were injured, … more than 200 of them in critical condition,” with injuries mostly found on the face, hands and abdomen.

The Iranian ambassador to Lebanon, Mojtaba Amani, was also injured in the explosions.

Who carried out the attack?

Many, including Hezbollah, point to Israel.

Israel and Hezbollah have been engaged in a mostly minor exchange of fire on the Lebanese-Israeli border since October 8. The day before, Hamas-led attacks on Israel killed 1,139 people, captured around 240 people and sparked Israel’s war on Gaza.

Recently, Israeli politicians and media have increasingly talked about military action against Lebanon to push Hezbollah back from the border and enable the return of the approximately 60,000 Israelis who were evacuated immediately after the attacks began.

“We hold the Israeli enemy fully responsible for this criminal aggression,” Hezbollah said in a statement. Israel will “surely receive its just punishment for this sinful aggression,” it added.

Despite a similar condemnation by Lebanese Information Minister Ziad Makary, Israel itself remains silent – ​​as it has in the past.

Why were there no similar explosions in the Gaza Strip?

Hamza Attar of the Ministry of Defence at King’s College London said: “You cannot use the same method in Gaza because Hamas is very well positioned in using the Internet compared to Hezbollah.

“They are very capable in the field of telecommunications,” he said of Hamas, stressing the group’s efforts to encrypt communications.

“They don’t use phones or cell phones. They have their own network, internet and communications and don’t need anything above ground,” he said.

We don’t know yet.

Some speculation has focused on the wireless network that the pagers rely on, suggesting that this may have been hacked, causing the system to send out a signal that triggered a response from the already compromised pagers.

“I think every Hezbollah member at some level has been attacked,” data analyst Ralph Baydoun told Al Jazeera.

He also pointed out that although Israel does not need to know the names of the recipients of the manipulated signal, it could collect valuable information after the detonations.

“If they had the satellites turned on, … they would know the names and locations of all the agents under attack … immediately when they asked for help. They would give away their locations,” he speculated.

Other analysts, such as former British Army officer and chemical weapons expert Hamish de Bretton-Gordon, suspected that Hezbollah’s pagers may have been tampered with along the supply chain and “wired to explode on command.”

When the pager’s lithium battery overheats, a process called thermal runaway occurs.

Essentially, a chemical chain reaction would take place, causing the temperature to rise and eventually causing the battery to explode violently.

However, it is anything but easy to trigger such a chain reaction on several devices that have never been connected to the Internet.

“There has to be a bug in the pager itself for it to overheat due to certain circumstances,” Baydoun said, speculating that those circumstances would most likely be a trigger introduced into the pager by tampered code.