The RCMP is defending its response to an anti-fracking protest in eastern New Brunswick that turned violent on Thursday, saying that police “have no choice but to react” when public safety is compromised.

Cmdr. Roger Brown told reporters Friday that officers seized firearms, as well as improvised explosive devices and “a large amount of ammunition, knives and bear spray” at the scene of the protest, outside the Elsipogtog First Nation reserve near Rexton, N.B.

At least 40 protesters were arrested Thursday after police were called in to dismantle a two-week-old blockade. Protesters were trying to stop seismic testing at the site of a proposed shale gas development.

The Mounties had been ordered into the area Thursday morning to enforce a court injunction to remove the blockade. Access had been blocked to a road leading to an energy compound owned by SWN Resources.

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When officers stormed the area where protesters were camped out, things quickly became violent. Molotov cocktails were thrown at officers and at least five police vehicles were set ablaze. Police responded with bean-bag rounds and tear gas, and nearby schools had to be locked down.

Brown said he supports the right to a peaceful protest, and noted that the site was calm earlier in the day.

“But when the situation deteriorates to a point where it is no longer safe, where the general public is not safe, I as a commanding officer, the criminal operations officer, have no choice but to react and do something that is for the safety of everybody involved,” Brown said.

“I am so thankful that nothing happened yesterday, because we could be having a totally different press conference today. We are so fortunate that this unfolded like it did.”

Brown said shots were fired during the incident, but he could not confirm from where. He said officers did not fire any live rounds.

Nine of those arrested were expected in court Friday to face various charges, including pointing a firearm, mischief, assaulting a police officer, violating a court-ordered injunction and uttering threats. The remaining 31 who were arrested were released and ordered to appear in court at later dates.

Police said the investigation is continuing and “additional charges are expected.”

The RCMP also said that early Friday morning, an attempt was made to burn down the Elsipogtog First Nation RCMP office. No one was injured, and the building sustained only minor damage.

Brown said he met with the Elsipogtog chief and council late Thursday to ensure that if protests continue, they do so “in a peaceful manner.”

Elsipogtog First Nation Councillor Robert Levi, who was among those arrested Thursday, said protesters will try to stay at the site despite the injunction.

"We're going to stay -- I mean, we have to," he said. "This is what our people have been fighting for."

The RCMP said in a statement Thursday it will continue to enforce the injunction.

"The public is reminded that a court injunction remains in effect and anyone who violates the conditions of that injunction could be arrested and face charges," the statement read.

‘Respect the law’

Earlier Friday, Federal Justice Minister Peter MacKay called on all sides to respect the law and "avoid violence and return to discussions.”

"That is what we're all encouraging and hoping for, but when violence erupts you can expect the police are there to keep the peace and to protect citizens,” MacKay said at a roundtable discussion on justice issues in Halifax.

The protesters want SWN Resources, which is owned by Houston-based Southwestern Energy, to stop seismic testing and leave New Brunswick.

The shale gas developer issued a statement Friday saying it is in the early stages of exploration in New Brunswick.

"Our employees are dedicated to the safety of people and the environment, as well as ensuring we are in full compliance with all regulations," it said.

New Brunswick Premier David Alward defended the RCMP's actions, saying they were in response to "outside influences."

"What I can say is the encampment that was in Kent County, the RCMP made an evaluation to say that that was not safe for people," Alward told reporters on Friday. "There were reports that had said there were weapons of various types, so this was not a law-abiding peaceful demonstration."

Elsipogtog Chief Arren Sock, who arrested during the protest and subsequently released, met with Alward Friday to try to resolve the issue.

One protester who attended Thursday’s demonstration said the events that unfolded were a "horrible nightmare."

"I keep on rubbing my eyes and thinking that this is just going to be a bad dream. And then I realized that this is real and it feels like a horrible nightmare, feels like a horror film, and it feels like hell on earth," Savannah Simon, of the Elsipogtog First Nation, told CTV Atlantic.

After the arrests, a number of "sympathy protests" sprang up in other parts of New Brunswick, as well as in southern Ontario and Winnipeg.

CTV News’ Todd Battis reported Friday afternoon that a growing number of people have been flocking to the site in support of the protesters, and more are en route.

Grand Chief Derek Nepinak, of the Assembly of Manitoba Chiefs, told CTV News Channel he will be travelling to New Brunswick on Saturday to lend support, “as well as to get a better understanding as to what is actually happening on the ground in the community.”

With files from CTV Atlantic's David Bell and files from The Canadian Press