At least 44 people were killed and many more injured in a stampede at the grave of a Jewish sage in northern Israel, as tens of thousands of devotees crowded the holy site after coronavirus restrictions were eased.

Prime Minister Benjamin Netanyahu called the stampede, among the worst civilian mishaps in Israeli history, “a heavy disaster”. The army was deployed on early Friday morning to help civilian rescue workers at what the army described as a “mass casualty event”.

“The Mount Meron disaster is one of the worst that the State of Israel has ever experienced,” said Netanyahu on a visit to the scene on Friday. “We are pained over those who have died. Our hearts are with the families as well as with the injured.”

At least 100,000 devout Jews had gathered at the grave of second-century sage Rabbi Shimon bar Yochai on Thursday evening for the Lag B’Omer festival, which traditionally involves a night of prayer, dance and bonfires. It was one of the first big gatherings in Israel — and among the largest in the world — since a mass vaccination campaign enabled the country’s public reopening.

The exact sequence of events is unclear. Footage from the scene at Mount Meron showed that some of the temporary scaffolding had collapsed. Separate reports said overcrowding had led to a stampede near the entrance to a narrow tunnel that leads to the grave, citing survivors who said they slipped and fell on the stairs.

Nearly all witnesses described an evening of prayer turning to chaos, with rescue workers forced to scramble over crowds to try and reach victims. Video on social media showed ultra-Orthodox men swaying and dancing in dense crowds minutes before the disaster.

“You could not tell where the pushing was come from, and there was nowhere to go. I just held [my brother] and we prayed,” said Isaac, a 19-year-old devotee searching for a friend at a hospital, according to a text message sent to his family.

Mobile phone networks were disrupted, and highway construction cleared away to allow rescue services to reach the site, which was already a vast traffic jam before the stampede.

Israel’s ambulance services told Ynetnews that most of the deaths were caused by severe overcrowding. The chief of the Israeli police’s northern command, Shimon Lavie, said he took “full responsibility” for the events, as powerful ultra-Orthodox political leaders demanded a full investigation.

Last year’s event was curtailed because of Covid-19 restrictions. This year’s event was permitted but authorities tried to limit the number of bonfires and health officials warned that it could be a coronavirus hazard.

Israel’s ultra-Orthodox minority forms a crucial backbone of Netanyahu’s coalition, and throughout the pandemic the government has been criticised for turning a blind eye to gatherings that breached coronavirus restrictions.

About 5,000 police officers were deployed to enforce coronavirus restrictions at the mystic’s tomb and media reports said police had already turned people away from the site before the accident.

Scuffles broke out earlier on Thursday evening between the police and the ultra-Orthodox attendees as authorities tried to enforce a green passport system to separate the vaccinated from the unvaccinated, according to videos posted on social media.

Helicopters evacuated the injured to local hospitals, where television news channels showed tents being set up to treat the wounded. A rescue worker told a local radio station that attempts to save those trampled were hindered by debris, and warned that more victims could be buried underneath.