A man was slashed with a sword outside a roller disco by an attacker reportedly wearing a “Make America Great Again” cap.

Police have launched a manhunt after the victim was left bleeding heavily on the pavement outside the Church of 8 Wheels in San Francisco on Friday night.

The victim was taken to hospital where he was treated for non-life-threatening injuries.

It is understood the victim attempted to grab the other man’s MAGA hat – a symbol of Donald Trump’s presidential campaign – during a dispute before the attacker pulled out a sword and slashed his hand.

A photo of the scene shows a red cap with “Make America Great Again” on the front in white lettering lying on the pavement near a pool of blood.

Inside a Make America Great Again rally in Chattanooga, Tennessee Show all 16 1 /16 Inside a Make America Great Again rally in Chattanooga, Tennessee Inside a Make America Great Again rally in Chattanooga, Tennessee Anti-Trump protesters gather outside of the rally Getty Inside a Make America Great Again rally in Chattanooga, Tennessee A supporter of the president waiting for the rally Getty Inside a Make America Great Again rally in Chattanooga, Tennessee Anti-Trump protesters wield picket signs Getty Inside a Make America Great Again rally in Chattanooga, Tennessee A Trump supporter outside of the Mckenzie Arena in Chattanooga prior to the President's appearance Getty Inside a Make America Great Again rally in Chattanooga, Tennessee Anti-Trump protesters gather outside of the rally with signs Getty Inside a Make America Great Again rally in Chattanooga, Tennessee A t-shirt for sale at the rally Lucy Gray Inside a Make America Great Again rally in Chattanooga, Tennessee A crowd gathers in waiting for the rally Lucy Gray Inside a Make America Great Again rally in Chattanooga, Tennessee A Trump memorabilia stand outside of the rally EPA Inside a Make America Great Again rally in Chattanooga, Tennessee Trump supporters cheer as the President arrives to the rally AP Inside a Make America Great Again rally in Chattanooga, Tennessee President Trump stands with Lee Greenwood as he sings 'God Bless the USA' to commence the rally Reuters Inside a Make America Great Again rally in Chattanooga, Tennessee A supporter listens as President Trump speaks EPA Inside a Make America Great Again rally in Chattanooga, Tennessee President Trump addresses supporters AP Inside a Make America Great Again rally in Chattanooga, Tennessee President Trump thanks Senate candidate Marsha Blackburn after her speech EPA Inside a Make America Great Again rally in Chattanooga, Tennessee Supporters of the president wield signs during the rally Getty Inside a Make America Great Again rally in Chattanooga, Tennessee Trump supporters cheer during the rally AFP/Getty Inside a Make America Great Again rally in Chattanooga, Tennessee President Trump exits the stage AP

David Miles, who manages the roller skating venue, said he ran outside after the attack with a first aid kit and tried to stop the bleeding as the victim was “just gushing blood”, the San Francisco Chronicle reports.

It is believed the victim chased after the man before realising the extent of his injuries.

Scott Sweeney, 24, told the newspaper he saw a man wearing the MAGA hat with a sword tucked into the back of his jacket about half an hour before the attack.

However he said he did not think it was a real sword until he later left the venue and saw the blood and hat on the ground.