PORTLAND, Ore. -- Hundreds of people, including several prominent state and local politicians, gathered to protest President Donald Trump's immigration ban at Portland International Airport on Sunday.

The rally was peaceful until about 5 p.m. when a counter-protester was assaulted. Portland Police officers moved in and surrounded the counter-protester and then moved him out of the protest area to receive medical attention.

PHOTOS: Sunday protest at Portland International Airport

The rally began at 2 p.m. The group of protesters started inside the airport, marched outside and then went back inside. Many of the protesters left around 5 p.m., when the rally was scheduled to end, though others stayed and continued to protest.

Sunday's rally was called the "NO BAN NO WALL march," according to the event's Facebook page. Five hundred people committed to attend on the page and more than 1,000 said they were interested in attending.

Oregon Senator Jeff Merkley, Congresswoman Suzanne Bonamici and Portland Mayor Ted Wheeler were in attendance at the protest. Each of the state and local leaders spoke to protesters and the media, and said they believed Trump's policies are unconstitutional and they are prepared to fight them.

Merkley, in a Sunday morning tweet, invited citizens to join him "in the fight to uphold our core values of liberty and justice for ALL."

Portland's Resistance leader Gregory McKelvey also tweeted he would be there.

This marks the second day of protests at the Portland airport in opposition to Trump's executive order banning legal U.S. residents and visa-holders from seven Mulsim-majority nations from entering the United States for at least 90 days.

RELATED: Protesters at PDX celebrate judge's ruling on Trump executive order