The eruv is literally a stick and string contraption that delineates an area in which Orthodox Jews can do a form of labor - carrying - that would otherwise be forbidden to them on the Sabbath except in their homes.
Wolfgang Duffal, one of the security guards hired by the ultra-Orthodox group, said Friday's clash nearly erupted into an all-out street fight.
"Up to 100 people were involved in the dispute," said Duffal.
"The [ultra-Orthodox] were like animals. There was a huge mob, and they tried to grab things out of people's hands to stop them from carrying things."
Duffal said that during one altercation, a group of Satmars "grabbed one guy's fur hat and threw it over the fence . . . and I think they hit him and beat him up."
And yesterday, Satmar members kept up the heat, harassing and taunting people on the street.
"I just got screamed at back there," Rabbi Yitzhak Stern said yesterday afternoon during a stroll down Lee Avenue with his four kids.
"You know the sign outside the hall on Bedford Avenue? That is discrimination. We are allowed to do what we do because there is a string around the area."
A man said the harassment and intimidation isn't kosher. "The Satmar group are the majority around here, and they want to impose their interpretation of the religious law on everyone," said the man.
"They harass and shout at anyone they see carrying anything in their hands or pushing a stroller on the Sabbath. It's not right."
I'm reminded of the religious police in Saudi Arabia. I've previously posted on the categories of religious fundamentalists - which transcend religious beliefs.