A Donald Trump supporter was knocked unconscious and suffered concussion after he was hit during a protest at Portland International Airport.

Grant Chisholm, 39, was with three other members of the Bible Believers Group who were holding a counter protest supporting Trump's immigration ban when he was assaulted.

The counter protest faced approximately 600 people who were demonstrating against the controversial measure.

These are the shocking scenes after a pro-Trump supporter is knocked out at a demonstration

Grant Chisholm was part of a counter demonstration at Portland International Airport. His Bible Believers Group were protesting in support of Trump's controversial immigration ban

Chisholm claimed a Trump opponent hit him three times on the head with a metallic object.

He told the Oregonian: 'They almost killed me tonight.'

The shocking video was posted on a 'Women for Trump' website. It shows the victim falling to the ground after he is punched.

Several people surround the victim until police arrived.

Chisholm said he was at the protest to preach and claimed one of the demonstrators asked him for a fight.

He was rushed to Legacy Emanuel Medical Center for emergency treatment but was released approximately two hours later after being treated for concussion.

Chisholm was with three friends when he was attacked in the airport's terminal building