Molotov cocktails were thrown at officers and at least five police vehicles were set ablaze during a confrontation on Thursday between the RCMP and protesters of a proposed shale gas development in New Brunswick.

The violence erupted near a New Brunswick First Nations reserve after protesters blockaded the highway leading to an energy compound, in an effort to stop seismic testing at the site.

RCMP moved in on the blockade near Rexton, N.B., on Thursday morning to enforce a court injunction to remove the blockade put up by members of the Elsipogtog First Nation.

Police arrested at least 40 protesters for firearms offences, threats, intimidation, mischief and violating the injunction, the RCMP said in a statement released Thursday afternoon.

Protester Melina Augustine, who says she was arrested for obstruction, described the confrontation to CTV Atlantic.

She said there were around 100 officers at the protest.

"It just got wild and they all tackled us down," she said, adding that her 67-year-old mother was tackled.

A councillor from the Elsipogtog First Nation said police used pepper spray on the crowd of protesters.

"They sprayed the crowd that was there," Robert Levi told The Canadian Press in an interview. "The chief was manhandled a little bit and all hell broke loose."

In a police statement, Const. Jullie Rogers-Marsh said "The RCMP has worked diligently with all parties involved in hopes for a peaceful resolution. Those efforts have not been successful."

"Tensions were rising, and serious criminal acts are being committed," she added.

The RCMP also said at least one shot was fired by someone who isn’t an officer.

Just before 9 a.m. on Thursday, police shut down a section of Route 11, located 10 kilometres south of Rexton, CTV Atlantic's David Bell reported from the scene. At 10 a.m., officers stormed the area where protesters were camped out.

Protesters were restrained in plastic handcuffs and loaded into a police van, Bell said. At least one protester was taken away by ambulance.

Bell added that media were being kept a few hundred feet away from the scene, but a number of protesters have filmed footage of the confrontation with officers on cellphone cameras.

APTN reporter Ossie Michelin told CTV News Channel that the protesters have been "waiting for the other shoe to fall."

"I know the RCMP has fallen under criticism for not acting sooner," Michelin said, noting that the RCMP have said they were waiting before acting on the injunction, in the hopes that a peaceful resolution would be found.

"But it looks like the RCMP grew tired of waiting and moved in this morning," he said.

Protesters had set up an encampment just over two weeks ago, blocking access to a compound belonging to SWN Resources, which stores equipment used to test for shale gas. SWN Resources is owned by Houston-based Southwestern Energy.

Michelin added that the current protest has its roots in an incident in June, when members of the Elsipogtog First Nation surrounded a seismic testing truck.

"People here are very concerned over the controversial practice of fracking," he said. "They say they want to make sure that these resource companies don't even get to the step where they can begin fracking. They want to stop the exploration dead in its tracks and put a moratorium on the whole shale gas industry in New Brunswick."

Levi said the protesters, including members of the First Nation, would try and 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."

A section of Route 134 was blocked by the RCMP on Sept. 29 after the protest began creeping onto the road.

In turn, protesters cut down trees on another part of Route 134 to block the entrance to the SWN compound.

Smaller solidarity protests were also held in other parts of the country Thursday, including Winnipeg and Caledonia, Ont.

Opponents of shale gas exploration warn of the environmental dangers linked to the process used to extract the gas – a process known as "fracking." But supporters say fracking concerns are over-exaggerated.

New Brunswick Minister of Energy Craig Leonard has said that the shale gas industry could help boost the province's economy. He claims that opponents to fracking are driven by ideology, not facts.

New Brunswick Premier David Alward and Elsipogtog Chief Arren Sock agreed last week to establish a working group, made up of members of the government, representatives from Elsipogtog and the energy industry, to find a resolution on the issue.

Since then, meetings have been held in Fredericton and Moncton.

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