(Tinley Park Police Dept.)

By Andrew Fies

A group of 18 people dressed in black, wearing masks, wielding steel batons and hammers and claiming to be extreme anti-racists allegedly stormed a suburban Chicago family restaurant in broad daylight to assault a meeting of alleged white supremacists, officials said.

Ten people were injured and at least three required treatment for head wounds as a result of the attack Saturday at the Ashford House Restaurant in Tinley Park, Ill., a quiet Chicago suburb. The restaurant sustained $15,000 in damages including broken plates, glasses and furniture.

"I've been mayor for 31 years," Tinley Park Mayor Ed Zabrocki tells ABC News, "and I've never heard of anything stranger than this."

Five of the attackers were caught and have now been charged with aggravated battery, mob action and criminal damage to property, all felonies. Brothers Jason, Cody and Dylan Sutherlin, along with Alex Stuck and John Tucker are all from Indiana. The men are connected to the Hoosier Anti-Racist Movement (H.A.R.M.) whose website now claims them as "The Tinley Park 5?.

Meanwhile the targets of their attack were about a dozen members of the Illinois European Heritage Association, a group linked to the "White Pride" group Storm Front. Two of these victims were also caught up in the police investigation following the incident: Steven Speers of North Dakota was arrested on an outstanding warrant for possession of child pornography and Francis Gilroy of Florida was charged with unlawful possession of a firearm by a felon.

A restaurant surveillance camera captured some of the melee on video and Zabrocki viewed it before it was turned over to prosecutors as evidence in the investigation.

"You see the door opens up, these 15, 18 people walk in. They've got hoods on, they've got masks on," Zabrocki said.

While the confrontation itself happens out of the camera's view, he said, "You see tables moving into view, food spilling on the floor. You see them marching out and you see some of the waiters taking swings at them."

Tinley Park police chief Steve Neubauer said neither of the groups involved had any connection to his town or the restaurant and he was struck by the randomness of the incident.

"There was a college graduation luncheon and a shower going on there. It's a nice little family restaurant. You take your mother in law there for mother's day for breakfast," Neubauer said.

The meeting of the Illinois European Heritage Association had been frequently mentioned on the "White Pride" webforum stormfront.org. It was called the "5 th Annual White Nationalist Economic summit" and promoted as an opportunity to "work for whites."

The Southern Poverty Law Center, which monitors extremist group activity, suggested that H.A.R.M. probably matched the names of those organizing the meeting on stormfront.org to those on a membership list of the neo-Nazi National Socialist Movement. But Beckie Williams, one of the attack victims, told the Chicago Tribune that the charge of racism is "ridiculous" and that her Heritage group was only meeting to discuss "economic hardships."

Meanwhile Zabrocki said he is angry about this "totally bizarre" incident for the law enforcement and emergency response it has required.

"This is going to cost us a bundle … to our town and a bunch of other towns that responded for you know, a bunch of idiots," he said. "And I'm referring to both sides."