Dozens of people died in the northern Israeli town of Meron on Thursday night after a stampede at a large public gathering to celebrate the Lag BaOmer Jewish festival.
Rescue services say at least 45 people were killed and some 150 hospitalized in the incident.
Scenes from Meron hours after the accident showed an ultra-Orthodox Jewish crowd in distress, with debris scattered across the ground.
Some survivors had lit candles for the victims while others prayed at a nearby wall.
Emergency services and ambulances "are treating dozens of injured," including "20 patients in a critical state," Zaki Heller, spokesperson for Magen David Adom, the Israeli emergency service, said in a statement.
Israeli media published an image of a row of bodies covered in plastic bags on the ground.
Dov Maisel, a member of the volunteer medical services association United Hatzalah, told DW, "What started out as a festival of joy, happiness and dance turned into Israel's worst tragedy."
"It's the first major event to occur after lifting COVID restrictions," he said, noting that people felt encouraged to "go out and practice their religious beliefs and ceremonies."
It was not immediately clear what caused the stampede.
Media reports initially said a section of stadium seating had collapsed at the event site. But officials later said it appeared that the casualties had been asphyxiated or trampled in the stampede.
Foreign ministers express their condolences
President Reuven Rivlin also tweeted that he was following the reports from Meron and praying for the recovery of the injured.
Israeli Prime Minister Benjamin Netanyahu described the incident as a "heavy disaster" and added: "We are all praying for the wellbeing of the casualties."
German Foreign Minister Heiko Maas wrote on Twitter: "Our thoughts are with the victims and their families."
India's External Affairs Minister was "deeply saddened at the tragedy" and wished "the injured a speedy recover."
Gathering held despite COVID risk
The annual pilgrimage for the feast of Lag BaOmer is staged in Meron around the reputed tomb of Rabbi Shimon Bar Yochai, a second century Talmudic sage.
Last year, the event was called off due to restrictions to curb the spread of the coronavirus.
Authorities had authorized 10,000 people to gather at the site of the tomb but organizers said more than 650 busses had been chartered from across the country, bringing 30,000 pilgrims to Meron.
Health officials had worried that crowding could pose a COVID-19 risk.
About 5,000 police were deployed to secure the event, with the police urging pilgrims to avoid incidents during the feast when bonfires are lit.
sri/aw (dpa, AFP, Reuters)