How did they explode and who is responsible?

At least 12 people including two children were killed and thousands more injured, many seriously, after pagers used by the armed group Hezbollah to communicate dramatically exploded across the country on Tuesday.

It is unclear how the highly sophisticated attack occurred, though Hezbollah has blamed its adversary Israel. Israeli officials have so far declined to comment.

Analysis of fragments from the pagers suggested they were made by the Taiwanese firm Gold Apollo, but the CEO denied this and said they had been made under licence by a company in Hungary. BBC calls to the company went unanswered.

On Wednesday afternoon there were reports of further explosions involving walkie-talkies in southern Beirut.

Here is what we know so far.

The blasts began in Lebanon’s capital Beirut and several other areas of the country at about 15:45 local time (13:45 BST) on Tuesday.

Witnesses reported seeing smoke coming from people’s pockets, before seeing small explosions that sounded like fireworks and gunshots.

In one clip, CCTV footage appeared to show an explosion in a man’s trouser pocket as he stood at a shop till.

Citing US officials, the New York Times said that the pagers received messages that appeared to be coming from Hezbollah’s leadership before detonating. The messages instead appeared to trigger the devices, the outlet reported.

Explosions continued for around an hour after the initial blasts, the Reuters news agency reported.

Soon after, scores of people began arriving at hospitals across Lebanon, with witnesses reporting scenes of mass confusion.

Analysts said the most likely explanation was a supply chain attack that saw the pagers tampered with during manufacture or transit.

Reuters quoted a Lebanese security source as saying that a small quantity of explosives had been placed inside the devices months ago.

Speaking to the BBC, one ex-British Army munitions expert, who asked not to be named, speculated that the devices could have then been triggered by a remote signal.

One Hezbollah operative told the AP news agency that the pagers were a new brand that the group had not used before. A Lebanese security official told the Reuters news agency that around 5,000 pagers were brought into the country about five months ago.

Labels seen on fragments of exploded pagers point to a pager model called the Rugged Pager AR-924. But its Taiwanese manufacturer Gold Apollo has denied any involvement with the explosions. When the BBC visited Gold Apollo on Wednesday local police were swarming the company’s offices, inspecting documents and questioning staff.

The founder, Hsu Ching-Kuang, said his company had signed an agreement with a Hungarian-based company – BAC – to manufacture the devices and use his company’s name. He added that money transfers from them had been “very strange”, without elaborating.

BBC Verify has accessed BAC’s company records, which reveal it was first incorporated in 2022. Its registered address reveals a nondescript building in a Budapest suburb, and repeated calls to its offices by the BBC on Wednesday went unanswered.

However its CEO Cristiana Bársony-Arcidiacono told NBC that she knew nothing about the explosions. “I don’t make the pagers. I am just the intermediate. I think you got it wrong,” she said.

Unnamed US and Israeli officials told Axios that detonating the pagers all at once was initially planned as the opening move in an “all-out” offensive against Hezbollah. But in recent days Israel became concerned Hezbollah had become aware of the plan – so they were set off early.

Israeli officials have not commented on the allegations, but most analysts agree that it seems likely it is behind the attack.

Prof Simon Mabon, chair in International Relations at Lancaster University, told the BBC: “We know that Israel has a precedent of using technology to track its target” – but he called the scale of this attack “unprecedented”.

Lina Khatib, from the UK-based Chatham House, said the attack suggested that Israel has “deeply” infiltrated Hezbollah’s “communications network”.

Prime Minister Najib Mikati said the explosions represented a “serious violation of Lebanese sovereignty and a crime by all standards”.

In its statement accusing Israel of being behind the attacks, Hezbollah said it held the country “fully responsible for this criminal aggression that also targeted civilians”.

Hezbollah has relied heavily on pagers as a low-tech means of communications to try to evade location-tracking by Israel. Pagers are wireless telecommunications devices that receive and display alphanumeric or voice messages.

They are much harder to track than mobile phones, which have long since been abandoned as simply too vulnerable, as Israel’s assassination of the Hamas bomb-maker Yahya Ayyash demonstrated as long ago as 1996, when his phone exploded in his hand.

In February, Hassan Nasrallah directed Hezbollah fighters to get rid of their phones, saying they had been infiltrated by Israeli intelligence. He told his forces to break, bury or lock their phones in an iron box.

Experts now say the directive, issued during a live televised address, may have forewarned Israeli intelligence operatives that the group would be seeking a new – likely lower tech – method of communications.

A source close to Hezbollah told AFP that two of those killed were the sons of two Hezbollah MPs. They also said the daughter of a Hezbollah member was killed.

Among the injured was Iran’s ambassador to Lebanon, Mojtaba Amani. Reports in Iranian media said his injuries were minor.

Hezbollah chief Hassan Nasrallah was not hurt in the explosions, Reuters reported quoting a source.

Lebanese Public Health Minister Firass Abiad said damage to the hands and face made up the majority of injuries.

Speaking to the BBC’s Newshour programme, he said: “Most of the injuries appear to be to the face and especially to the eyes and also the hand with some amputations, whether it’s in the hands or the fingers, and some of them have injuries to their flank.”

He added: “The vast majority of the people who are presenting to the emergency rooms are in civilian clothes, so it’s very difficult to discern whether they belong to a certain entity like Hezbollah or others…

“But we are seeing among them people who are old or people who are very young, like the child who unfortunately died… and there are some of them who are healthcare workers,” the minister said.

Outside of Lebanon, 14 people were injured in similar blasts in neighbouring Syria, according to UK-based campaign group the Syrian Observatory for Human Rights.

Hezbollah is allied with Israel’s arch-nemesis in the region, Iran. The group is part of Tehran’s Axis of Resistance and has been engaged in a low-level war with Israel for months, frequently exchanging rocket and missile fire across Israel’s northern border. Entire communities have been displaced from both sides.

The blasts came just hours after Israel’s security cabinet made the safe return of residents to the north of the country an official war goal.

Prime Minister Benjamin Netanyahu told a visiting US official that Israel would “do what is necessary to ensure its security”.

Earlier on Monday, Israel’s domestic security agency said it had thwarted a Hezbollah attempt to assassinate a former official.

Despite the ongoing tensions, observers say that until now both sides have aimed to contain hostilities without crossing the line into full-scale war. But there are fears that the situation could spiral out of control.

Additional reporting by Frances Mao