(CNN)The Israeli government knew to expect trouble on Tuesday night. It was Lag Ba-Omer, a Jewish holiday traditionally celebrated in Israel with mass gatherings around roaring bonfires. For the devout ultra-Orthodox community, it is an occasion for making a pilgrimage to Mt. Meron in the country's north, where the second-century Rabbi Shimon bar Yochai is buried.
Why some ultra-Orthodox Jewish communities defy social distancing
Thousands usually visit the site at this time of year, but in the midst of the coronavirus pandemic the Israeli government issued a decree ordering that from May 7 to 13, "gathering on the area of Mt. Meron will be prohibited except for local residents or people who need to go there for work."
It didn't work. Hundreds of ultra-Orthodox Jews turned up on Mt. Meron Tuesday in defiance of the ban, according to the police.
"Suspects stormed a closed off mountain area and caused wide-scale disturbances that included throwing rocks at police and causing damage," police spokesman Micky Rosenfeld said.
Through the evening, the numbers of people arrested kept ticking up: first 100, then 200, then more. In the end, 320 people were arrested for violating health and security measures, Rosenfeld said.
The mass arrests are the latest incident in a global trend with dangerous consequences -- a small but committed segment of the ultra-Orthodox Jewish community from Israel to London to New York refusing to obey social distancing orders.
Two weeks before the Mt. Meron arrests, a large crowd turned out for the funeral of a prominent rabbi in the heavily ultra-Orthodox Jewish neighborhood of Williamsburg in Brooklyn, New York.
A week before that, police in London were called -- twice -- to disperse an ultra-Orthodox Jewish wedding in London's Golders Green neighborhood.
In Israel, at least, the results for fervently observant Jews have been serious. About 50% of Israel's coronavirus cases have been in largely ultra-Orthodox municipalities, according to a CNN analysis of Ministry of Health data through May 12. The country is about 14% ultra-Orthodox.
Israel has more than 16,000 confirmed cases of coronavirus and 265 deaths, according to data from Johns Hopkins University as of Thursday.
The reasons that some ultra-Orthodox Jews have been reluctant to change their behavior are deep-seated: religious, cultural and demographic, experts said.
"It's the center of their life, the religion, and they can't live without it," said Gilad Malach, the director of the Ultra-Orthodox in Israel Program at the Israel Democracy Institute. "The most important thing in their life is their religious behavior and traditions, and it's very hard for them to change it. They see it as a religious obligation."
The community's lifestyle is centered around religion -- and observant Jews gather three times a day to pray in a group.
"Prayer, according to Judaism, is something you can do alone -- but the most favorable way to do it is in public. 'In public' in Jewish law means ten male adults. This is called the minyan, it's kind of a quorum, and you do it usually in synagogues," said Benjamin Brown, professor of Jewish thought at the Hebrew University of Jerusalem.
"Now synagogues are usually small places, crowded, it's a very easy place to get an epidemic," Brown said, so when it became clear that coronavirus was spreading worldwide, Israel's government ordered synagogues and schools to close. Most complied, even within the most religious segment of Israeli society -- but some of the most extreme ultra-Orthodox did not.
Many ultra-Orthodox Jews live largely cut off from society, intentionally limiting their access to outside influences and relying on their rabbis for guidance.
"Just half of the ultra-Orthodox society have access to the internet, and some of them just have it at work, and some of them don't have TVs," Malach said.
That's because they don't want to be exposed accidentally to improper influences, Brown said.
"The internet is a source of spiritual danger -- which includes first sex, then violence, fake news, gossip and slander. All of these are considered very severe" violations of religious norms, Brown said.
As a result, when the Israeli government started issuing warnings through multiple channels -- including maps showing where cases had been detected so that people could avoid them and self-quarantine -- the most sheltered ultra-Orthodox communities didn't see them, Malach said.
That left them relying on their rabbis for guidance -- including Rabbi Chaim Kanievsky, 92, who initially said there was no need for religious school closures, Brown said.
Bnei Brak, the heavily ultra-Orthodox city where Kanievsky lives, became one of Israel's coronavirus hot spots, along with parts of Jerusalem, which also has a large ultra-Orthodox population.
The community's large families and relative poverty make social distancing very difficult.
"Part of their way of life is having many children -- seven, eight, nine children is very common," Brown said. "They live in small apartments. You can't have social distancing, you can't have isolation, definitely not when your children are not in school dormitories but came home."
Malach put it bluntly: "They are stuck at home, they have nothing to do, and this makes it harder to follow the instructions."
Rabbi Herschel Gluck, an ultra-Orthodox rabbi in London's Stamford Hill neighborhood and community activist honored by Queen Elizabeth II for his interfaith work, told CNN only a small min