(CNN) -- At least 40 people were arrested Thursday in New Brunswick, Canada, when protests over gas exploration turned violent, according to authorities.
At least one shot was fired by someone other than police, and at least five police vehicles were set on fire, Royal Canadian Mounted Police said in a statement.
"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," said Constable Jullie Rogers-Marsh of the New Brunswick RCMP.
Elsipogtog First Nation Chief Aaron Sock was among those arrested in the clashes.
According to CBC News, he is the leader of a group of that has been blockading Route 134 near Rexton since September 30. Protesters are reportedly angry about the government and shale gas companies moving forward with work in the area.
"The more the government ignores the situation, the greater the potential for this to escalate," said T.J. Burke, a lawyer for the Elsipogtog First Nation.
Police said they were investigating suspected explosive devices at the scene. Molotov cocktails were thrown, they said.
Those arrested were detained for various offenses, including firearms offenses, uttering threats, intimidation, mischief and refusing to abide by a court injunction on Route 134.
Route 134 at Rexton and Route 11 between Richibucto and Sainte-Anne-de-Kent were closed to traffic.
The situation was ongoing and dangerous, said Rogers-Marsh.