British police on Sunday detained six people after a fight at a London-area synagogue.
According to the Jewish Chronicle, the street fight occurred between party-goers leaving a house and local Jews early Sunday morning.
A local police spokesman told the Jewish Chronicle that authorities view the incident as grave.
The brawl at the Stamford Hill synagogue Ahavat Torah was filmed and uploaded to YouTube. In the video, the synagogue's windows appear broken and kippah-wearing men can be seen holding chairs to ward off the apparent assailants.
The Jerusalem Post reported that 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. From the video, it is unclear whether those words were uttered.
Earlier this year, British police stepped up security in Jewish areas of the country after a deadly attack at a Paris kosher supermarket.
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 last week 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 Jewish leaders, according to British media.
Want to enjoy 'Zen' reading - with no ads and just the article? Subscribe todaySubscribe now