Updated

One day after denouncing "extreme radicals" and calling for a more civil discourse regarding President Obama's plan to overhaul the nation's health care system, members of the Service Employees International Union utilized those same aggressive tactics to spread their own message, critics of the union say.

SEIU Healthcare Chairman Dennis Rivera has blamed radicals and "corporate front groups" for the recent confrontations at town hall events, including one last week in Missouri where an SEIU staffer was among six people arrested for misdemeanor assault and other crimes.

"At the same time that America's families are seeking relief from fast-rising and unaffordable health care costs, extreme radicals and corporate front groups are trying to derail health insurance reform by disrupting public meetings," Rivera said in a statement last Thursday.

"While SEIU and allies across the country are staging more than 400 events to promote a real discussion on the country's need for healthcare reform, these 'Astroturf' organizations are spreading ludicrous, discredited myths designed to scare people away from much-needed reform."

Rivera challenged anyone attending the public meetings to sign a pledge to "learn and contribute" to the public discourse without being disruptive or disrespectful.

But later that day, a St. Louis man was attacked, allegedly by an SEIU staffer and another man, outside of a town hall event with Rep. Russ Carnahan, D-Mo.

Kenneth Gladney, 38, was handing out "Don't Tread on Me" flags for the Tea Party movement, when he says he was called a racial slur and struck. Gladney, who is black, suffered injuries to his knee, back and shoulder.

"I didn't ask for this," Gladney told FOX News on Tuesday. "I was just there to do a job."

David Brown, Gladney's attorney, said his client is considering filing a lawsuit against SEIU and Elston McCowan, an SEIU staffer and reverend who Gladney claims uttered the racial slur. It was not immediately clear whether Gladney filed a complaint with police.

McCowan told the St. Louis Post-Dispatch that Gladney was the one who acted violently.

"Out of nowhere, the guy just assaults me," McCowan told the newspaper.

Brown, meanwhile, refuted that claim, noting that McCowan was arrested and not Gladney.

"It's absolutely ludicrous that Mr. Gladney attacked [McGowan], that's just spin by the unions," Brown told FOXNews.com on Monday. "My client was merely trying to address his freedom of speech and that's when he assaulted him."

Neither the SEIU nor McCowan replied to multiple calls for comment.

Officer Rick Eckhard, a spokesman for the St. Louis County Police, said six people were arrested outside Carnahan's event, including a Post-Dispatch reporter. The six have not yet been identified, he said.

"The investigation is continuing," Eckhard told FOXNews.com, adding that investigators continue to seek witnesses and video accounts of the incidents. He said police officials are expected to meet with the St. Louis County counselor's office later this week to determine if charges will be pursued.

Among the six arrests, two men were arrested for misdemeanor assault; one woman was arrested for misdemeanor assault and destruction of property; one woman was arrested for interference and resisting arrest; one man was arrested for peace disturbance; and Post-Dispatch reporter Jake Wagman was arrested for allegedly interfering.

If convicted of misdemeanor assault, those individuals face up to one year in jail.

In a statement released last Friday, the SEIU denounced claims that "GOP operatives are rushing to paint [the incident] as SEIU thug violence."

"That couldn't be further from the truth," the statement by SEIU Missouri State Council Executive Director Brandon Davis read. "In fact, the Reverend, a St. Louis Post-Dispatch reporter and others who attended in hopes of a peaceful dialogue about our nation's healthcare crisis, endured the latest attempt by right-wing fringe groups to hijack the democratic process through violence if necessary. Last night, the Teabaggers' violent tactics broke and dislocated the shoulder of the Reverend."

"Let's be clear: These groups, backed by insurance companies and corporate front groups, want nothing more than to preserve the status quo system of rationing, where HMOs choose doctors, and insurance companies deny us the care we need. Their dearest hope is that by resorting to outrageous charges if Nazism and euthanasia, they can make the American public too afraid to support real reform."

The SEIU -- with 2 million members in the U.S., Canada and Puerto Rico -- is the fastest-growing union in North America, and it reportedly spent up to $60 million last year to help elect President Obama. Its mobilizing members in three divisions -- health care, public services and property services -- have been easily spotted clad in purple T-shirts at recent town hall events nationwide.

According to its Web site, SEIU is North America's largest health care union, with more than 1.1 million nurses, doctors, lab technicians, nursing home employees and home care workers among its members. The union advocates for providing mandatory health care with a government-run insurance option and increased federal funding for training and upgrading the health care workforce.

With more than 300 local union affiliates and 25 state councils across North America, it would stand to profit from increased health-care employment, since roughly half of its members are employed within the health care field.

"A significant federal investment in appropriate training and education of the non-physician workforce is needed," the union's Web site reads. "Training in new technologies, teams, and systems must be provided to both incumbent healthcare workers and new recruits.... Support should be provided to recruit and train a workforce that reflects the diversity of the communities it serves."

Ernest Istook, a distinguished fellow at the  Heritage Foundation and a former U.S. congressman from Oklahoma, said the union will also gain "expanded" political power and membership with the passage of Obama's health care proposal, which would translate to increased funds for its coffers as well.

"[SEIU President Andrew Stern] has been very aggressive to push the SEIU to the top pinnacles of power," Istook told FOXNews.com. "And every time they are a major player in any issue, they can accumulate more power and increase desire to organize even more broadly."

Istook said critics of the union are concerned with perceived efforts to be "deliberately provocative" at town meetings across the country in order "to blame and discredit" individuals who oppose Obama's proposal.

"There is a real concern I know of among many of the people on the opposite side of the union and the president that this could be developing," Istook told FOXNews.com. "If you say the other side is doing it and you're doing it too, what does that tell you?"

Istook said the union's heavy presence at those town hall meetings speaks volumes as to its motive.

"They see this as a challenge to their ability to organize and be visible," he said. "They see it as a challenge and they want to rise to that challenge."