More than 1,000 people, including Hezbollah fighters and medics, were wounded on Tuesday when the pagers they use to communicate exploded across Lebanon, security sources told Reuters.

A Hezbollah official, speaking on condition of anonymity, said the detonation of the pagers was the “biggest security breach” the group had been subjected to in nearly a year of war with Israel.

Israel and the Iran-backed Hezbollah have been engaged in cross-border warfare since the Gaza war erupted last October, the worst such escalation in years.

The Israeli military declined to comment on Reuters inquiries about the detonations.

Iran’s Mehr news agency said the Iranian ambassador to Lebanon, Mojtaba Amani, was injured by one of the blasts. Reuters could not immediately confirm the report.

Wave of explosions lasted an hour

A Reuters journalist saw ambulances rushing through the southern suburbs of the capital Beirut, a Hezbollah stronghold, amid widespread panic. A security source said that devices were also exploding in the south of Lebanon.

At Mt. Lebanon hospital, a Reuters reporter saw motorcycles rushing to the emergency room, where people with their hands bloodied were screaming in pain.

The head of the Nabatieh public hospital in the south of the country, Hassan Wazni, told Reuters that around 40 wounded people were being treated at his facility. The wounds included injuries to the face, eyes and limbs.

The wave of explosions lasted around an hour after the initial detonations, which took place about 3:45 p.m. GMT. It was not immediately clear how the devices were detonated.

Lebanese internal security forces said a number of wireless communication devices were detonated across Lebanon, especially in Beirut’s southern suburbs, leading to injuries.

Groups of people huddled at the entrance of buildings to check on people they knew who may have been wounded, the Reuters journalist said.

All medical workers called in to help with patient influx

Regional broadcasters carried CCTV footage that showed what appeared to be a small handheld device placed next to a grocery store cashier where an individual was paying spontaneously exploding. In other footage, an explosion appeared to knock out someone standing at a fruit stand at a market area.

Lebanon’s crisis operations centre, which is run by the Health Ministry, asked all medical workers to head to their respective hospitals to help cope with the massive numbers of wounded coming in for urgent care. It said health-care workers should not use pagers.

The Lebanese Red Cross said more than 50 ambulances and 300 emergency medical staff were dispatched to assist in the evacuation of victims.

Hezbollah fired missiles at Israel immediately after the Oct. 7 attacks by Hamas gunmen on Israel. Hezbollah and Israel have been exchanging fire constantly ever since, while avoiding a major escalation as war rages in Gaza to the south.

Tens of thousands of people have been displaced from towns and villages on both sides of the border by the hostilities.