Mayor Ted Wheeler was tear gassed in downtown Portland early Thursday morning, according to video and posts on Twitter from a New York Times journalist.

The video shows Wheeler, wearing goggles and a face mask amid a crowd of people, hold his nose and close his eyes in distress as a cloud of tear gas drifts by him.

"It stings. It's hard to breathe. I can tell you with 100% honesty I saw nothing that provoked this response," Wheeler said to the Times camera. "I'm not afraid but I am pissed off."

It's unknown at this time who is responsible for deploying the tear gas and there is nothing to indicate the mayor was targeted. Portland Police said they did not deploy any CS gas, a commonly used type of tear gas.

CNN has reached out to the mayor's office for additional comment.

The video appeared to come after Wheeler joined crowds to listen to protesters and answer their questions in response to violent clashes between demonstrators and federal forces, whose camouflage, troop-like uniforms and aggressive tactics have exacerbated the protests.

"It is an unconstitutional occupation," Wheeler told the crowd. "The tactics that have been used by our federal officers are abhorrent. They did not act with probable cause, people are not being told who they are being arrested by, and you're been denied basic constitutional rights."

President Donald Trump said federal officers were sent to the city to protect federal property, but protesters and local leaders have strongly opposed their presence. Demonstrations, many of which have been peaceful, have been ongoing for more than 50 days.