A Hillary Clinton supporter was arrested outside the Democratic nominee's rally in Pittsburgh on Saturday for attacking an elderly man.

Joshua Sturman, 23, walked over to a group of protesters holding Donald Trump signs across the street from the David L. Lawrence Convention Center and attempted to light an American flag on fire before tackling a man to the ground according to the criminal complaint in the case.

He was apprehended by police on the scene soon after and is now facing charges of simple assault, disorderly conduct, causing or risking catastrophe and recklessly endangering another person.

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Not good: A Hillary Clinton supporter attacked a pro-Trump protester in Pittsburgh on Saturday afternoon (victim Richard Dillon above)

Culprit: Joshua Sturman (above with bandana around his neck) went after Richard Dillon when the man tried to rip a flag he was trying to burn from out of his hands

CBS Pittsburgh reports that the group of Trump supporters were standing shoulder-to-shoulder when Sturman approached the group around 5pm on Saturday afternoon.

Sturman, who is originally from California, had on a backpack and bandana, and red paint all over his hands.

He lit the American flag on fire as he neared the group, and the protesters quickly attempted to put out the flame, with many saying they feared it could have been doused with an accelerant.

This made Sturman angry according to the criminal complaint, and at that point he threw a man to the ground when the elderly gentleman tried to get the flag out of his hands.

Video of the incident shows Sturman as he is getting off the man and his friends try to get him to leave the scene, but it is too late, with police already there and quickly taking the young man away.

The Pittsburgh-Tribune Review interviewed Richard Dillon, the 67-year-old man who was attacked by Sturman, shortly after the incident.

'Symbolically, he was saying, "I will burn down everything you stand for" - beginning with the flag, Old Glory,' said Dillon, who is a Tea Party organizer in the area.

'We cannot let the country be commandeered by people like that.'

Jail time: Police who were patrolling the area quickly apprehended Sturman (above) and took him into custody

Off they go: Sturman is now facing charges of simple assault, disorderly conduct, causing or risking catastrophe and recklessly endangering another person (above being led away)

Another prop-Trump supporter who was at the scene, Tricia Cunningham, said: 'You ain't burning our flag. I'm the daughter of a Marine. There is no First Amendment when it comes to destroying the United States, as far as I am concerned.'

Sturman was later photographed sticking his tongue out at the group after being put in handcuffs by police.