British police have arrested six people following an anti-Semitic incident at a Stamford Hill Synagogue in London.
The Jewish Chronicle reported a street fight occurred between party-goers leaving a house and local Jews early Sunday morning.
A video of the incident showed around 10 members of the synagogue having to defend themselves with chairs and makeshift clubs as the apparently drunk youths attempt to force their way in through a set of double doors.
A local police spokesman said authorities view the incident as grave.
In the video, the synagogue's windows appear broken and kippah-wearing men can be seen holding chairs to ward off the apparent assailants.
Police were treating the incident as an anti-Semitic crime, and said one congregant "described the mob as shouting 'we will kill you'" during the attack.
British police have stepped up security in Jewish sites around the country after a deadly attack at a Paris kosher supermarket in January that killed four Jews.
The Community Security Trust (CST), which provides security advice to Britain's estimated 260,000 Jews, said police in London and Manchester in northern England had agreed to increase patrols at synagogues and other venues over the next days.
British Prime Minister David Cameron has announced that Jewish schools and synagogues will get 10 million pounds a year for security, following attacks at Jewish sites across Europe in recent months.
"At a time when once again the Jewish communities of Europe feel vulnerable, and when anti-Semitism is at record levels here in Britain, I will not stand by, I will not turn a blind eye," Cameron told a dinner of CST last week.