(ABC News)

Police and organizers shut down proceedings at one of Missouri's largest caucuses today, as Ron Paul supporters feuded with local GOP leaders.

"It's like the Hatfields and the McCoys around here," St. Charles County's former GOP chairman told ABC News, after police arrived on-scene with a helicopter and removed Paul backers.

In St. Charles, an exurb of St. Louis and one of the state's largest GOP counties, Paul supporters sought to elect their own chairman and adopt their own rules when proceedings opened - both of which are part of standard caucus rules and procedure. But as they argued with the caucus chair, Paul supporters held video cameras - against caucus rules, according to a GOP official who was there - and things became contentious.

"It turned into a little food fight within the caucus, between the caucus chairman trying to control the caucus and certain elements, I guess with Ron Paul, trying to be heard," said Tom Kipers, a former chairman of the St. Charles GOP, who attended the caucus at Francis Howell North High School.

An off-duty police officer, hired as security, eventually filed a trespassing complaint against the Paul supporters and notified on-duty police in the area municipality of St. Peters, who, along with police from other jurisdictions, arrested two Paul supporters and ended the caucuses early. A joint-jurisdictional police helicopter arrived on the scene. Kipers said about 10 officers arrived in total.

"Two people were arrested for trespassing after receiving numerous warnings to leave the school property," the St. Peters police said in a press release. "Both subjects were transported to St. Peters Justice Center where they were booked for Trespassing and released on a summons."

The St. Peters police identified the Paul supporters as Brent Safford, 45, of O'Fallon, Mo., and Kenneth Suitter, 55, of St. Charles.

Caucus business never really got started. The St. Charles GOP said in an official statement that it still plans to send delegates to the congressional-district and state conventions, but none were elected at the caucus on Saturday.

Saturday's episode was a near repeat of 2008, when Paul backers succeeded in overwhelming other factions at the St. Charles caucus, according to Kipers. Their elected delegates were subsequently tossed from the congressional-district convention for being verifiable Libertarians (by primary voter rolls) and not Republicans, although Missouri has no voter registration by party.

At the state convention, in a spirit of reconciliation according to Kipers, they were reinstated and the officials who had barred them were themselves barred for having done so.

"Did I expect this to happen? Kind of," Kipers said of Saturday's episode. "That's why we hired … policemen."

It's too early to tell which candidate performed best, and the Missouri GOP said anecdotal evidence indicates that very few counties chose to "bind" their delegates to any particular candidate.

The county caucuses are Missouri's main event in the 2012 primary season. There will be no traditional "winner": caucusers did not vote on presidential candidates, even in a "straw-poll" or "beauty-contest" sense, as in Iowa. Instead, caucusers chose first-tier delegates to Missouri's congressional-district and state conventions, who will then elect and allocate 49 of the state's 52 national delegates.

Rick Santorum won the state's nonbinding Feb. 7 primary, 55 percent to Mitt Romney's 25 percent. Newt Gingrich was not on the ballot, having made no attempt to qualify. The state party tried to cancel that event after a complex intra-state political saga.

Santorum supporters prevailed in Chesterfield, one of the largest caucus sites in St. Louis County, the only Missouri county holding multiple caucuses. Attendees elected slates of first-tier delegates who support Santorum, according to a local GOP official.

Paul supporters, meanwhile prevailed in Boone, a mid-sized county that encompasses Columbia and the University of Missouri. The county elected a slate of 48 Paul-supporting delegates and five who back Romney, the local GOP chairman said.

Paul supporters and local officials get along well in Boone, chairman Bruce Cornett said, although one 75-year-old county GOP member referred to them as "loud" and "obnoxious" at Saturday's event.

The caucuses won't end until next week. Nearly all the caucuses took place today, but Jackson County, which encompasses Kansas City and is one of Missouri's largest counties by GOP votes, will not caucus until March 24.