Three north London Jewish schools have closed for the day, some citing planned protests in support of Palestinians.
Parents at one school were told to keep their children inside because "of the risk of violence on the streets".
Menorah High School in Brent, Torah Vodaas Primary School and Ateres Beis Yaakov, both in Barnet, sent letters to parents announcing the closures.
The Community Security Trust, a charity providing security advice for British Jews, said schools should remain open.
The head teacher of Menorah High School for Girls, a state secondary school with 389 pupils, said the decision to close her school was made "in view of the planned protests".
In a letter seen by the OceanNewsUK, Esther Pearlman told parents: "Please be aware that this difficult decision has been reached because the [sic] of the risk of violence on the streets.
"The police are concerned that as the girls are not in school, they will venture outdoors and have asked us to advise you that it is incumbent on you as parents that your children remain indoors."
The chair of the school, David Landau, told OceanNewsUKToday Programme that most Jewish schools were not closing because there was not "an immediate risk" to the community and they did not want to "spread panic".
But, he said: "We have this situation where where we have an international day of rage called for. We've had horrible demonstrations in London openly displaying antisemitism and celebrating Jewish deaths.
"Individually, our school is fairly isolated from the community. We're out there out there on our own and we felt there was significant risk to the kids, ultimately we're worried that on a day like this that an individual might do something outstandingly stupid and it's very difficult to control against that."
The letter to parents at Ateres Beis Yaakov, a small primary school with 35 pupils enrolled, mentioned a call from former leader of Hamas Khaled Meshaal for protests across the Muslim world on Friday, in support of the Palestinians.
The letter said the school's decision was made "in the interest of the safety" of pupils.
Meanwhile, parents of children at Torah Vodaas Primary School, a boys' school with 372 registered pupils, were told they received advice from Rabbi Avrohom Gurwitz, a prominent leader in the Jewish Haredi community.
"We live in unprecedented times," parents were told.
"Although there is no specific threat to our school, we should not have school tomorrow.
"We appreciate the challenges and demands that this is putting on you and it is not a decision that has been taken lightly, but we need to do what is best for our precious children," the letter seen by the OceanNewsUK said.
Despite the concerns, a spokesman for the Community Security Trust (CST) said its advice was for schools to stay open.
"CST's advice to Jewish schools remains that Jewish life should continue and schools should remain open as normal.
"All Jewish schools have security guards that are paid for by the government, which has today pledged a further £3m towards the cost of security guarding in addition to the measures that are already in place."
This refers to an announcement from Prime Minister Rishi Sunak that extra money would be given to protect schools, synagogues and other Jewish community buildings.
The money will be given to the CST, which has recorded 139 antisemitic incidents in the last four days - a fourfold increase compared to the same period in 2022.
Correction: This story has been amended to make it clear the call for protests was in support of the Palestinian people, not Hamas.
