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The group walking around openly armed with assault rifles and roaming the streets of Ferguson, Missouri, overnight Monday in a confusing display were within the bounds of state law in their actions — and told NBC News they are doing what all Americans should: exercising their rights.

The handful of members of the right-wing citizen militia group known as the "Oath Keepers" told reporters that they have licenses to carry firearms.

It wasn't immediately clear whether they planned to return to the St. Louis suburb on Tuesday night — following a flare up of violence on the one-year anniversary of the fatal police shooting of black teenager Michael Brown.

St. Louis County authorities declared a state of emergency and more than 100 people were arrested Monday during a second night of protests.

The Oath Keepers, who were also in Ferguson during last year's unrest, said they returned to protect businesses and certain reporters.

If the Oath Keepers decide to hit the streets again, a voter-backed amendment passed last year makes it legal to open carry a firearm with a permit — and goes as far as invalidating municipal bans against it, said Anders Walker, a constitutional law professor at St. Louis University. The city of St. Louis was among the municipalities that had such a prohibition.

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The revised statute says anyone permitted to carry a gun can "briefly and openly display the firearm to the ordinary sight of another person, unless the firearm is intentionally displayed in an angry or threatening manner, not in necessary self defense."

What the Oath Keepers are doing is as "straightforward legally as this gets," said Greg Magarian, a professor of law at Washington University in St. Louis. "This is a state with extremely permissive gun carry laws."

The county being in a state of emergency doesn't have an effect on the law either, added Allen Rostron, a University of Missouri-Kansas City constitutional law scholar and professor.

When asked whether they confronted the Oath Keepers, the St. Louis County Police Department again told NBC News that it was consulting with the St. Louis County Prosecuting Attorneys Office about the issue.

County Police Chief Jon Belmar stated that the group's presence has been both "unnecessary and inflammatory."

The Oath Keepers' St. Louis Facebook page describes itself as a nonpartisan association of "current and formerly serving military, police, and citizens who pledge to fulfill the oath to defend the Constitution."

But the fact that the few Oath Keepers in Ferguson overnight were all white men and were permitted to roam heavily armed in a mostly black community has worried some about perceptions of racial inequality.

"They were able to hold their guns out in public because it's an open carry state, but if you're African American in the state of Missouri and you have a rifle in an open carry state, you're gonna be shot,” Democratic State Sen. Maria Chappelle-Nadal told NBC News. “And so there is one rule for white gun owners and another rule for black gun owners."

Magarian questioned what would happen in a test case where black men were open carrying in a white suburb.

"Would they be treated the same way?" he asked.

Larry Kirk, an Oath Keepers member and a police chief of a rural Missouri community, told NBC News that even if people aren't happy with the group's presence in Ferguson, they are there to ensure police and government aren't overreaching citizens' rights.

"Whether we are comfortable with somebody exercising their right, we still have to be able to have them exercise that right so we don't lose it," Kirk said.