Authorities say the incident at Givat Zeev, in which scores of ultra-Orthodox Jews had gathered to pray to mark the beginning of Shavuot, took place in a "dangerous" building with no permits for use.
Two Israeli citizens have died and more than 150 were injured after a tiered seating structure collapsed at a West Bank synagogue during prayers for Shavuot, a major Jewish holiday.
The bleacher at the incomplete building was packed with ultra-Orthodox worshippers when the incident occurred on Sunday evening.
A spokesman for Magen David Adom, Israel's national medical emergency service, said a man in his 50s and a 12-year-old boy had been pronounced dead by paramedics.
Another 157 people were treated for injuries, with military search and rescue troops and army helicopters deployed to convey patients from Givat Zeev, a settlement just outside Jerusalem, to hospital.
The collapse comes weeks after 45 ultra-Orthodox Jews were killed in a stampede at a religious festival in northern Israel, triggering widespread criticism of the extensive autonomy granted to the country's politically powerful ultra-Orthodox minority.
The Mayor of Givat Zeev has said the building was unfinished and dangerous, and that the police had ignored previous calls to take action.
Jerusalem police chief Doron Turgeman also said the disaster was a case of “negligence” and will probably lead to arrests, while Deddi Simhi, head of Israel Fire and Rescue, told Israel's Channel 12: "This building is not finished. It doesn’t even have a permit for occupancy, let alone holding events."
Television footage from the scene showed the building was incomplete, with exposed concrete and boards visible.
Last year, many ultra-Orthodox communities in Israel openly flouted coronavirus restrictions, contributing to high outbreak rates in their communities and angering the wider public.