Footage has today appeared online of the violence outside the Ricoh Arena which marred yesterday's Coventry City v Sunderland match.
The Black Cats were backed by 5,000 travelling fans at the League One game, which ended in a 1-1 draw.
But many were shocked at ugly scenes outside the ground, as visiting fans headed back to their coaches.
Coventry yobs were reportedly trying to break through metal barriers which were meant to keep rivals fans apart.
Footage which has appeared on YouTube shows skirmishes in the area outside the coach park.
And police and stewards are shown doing their best to keep two large groups of fans apart on a hill overlooking the coach park.
There were reports of Coventry fans gathering stones and pelting them at the Sunderland coaches, with one suffering a broken window.
One 42-year-old supporter from Houghton, who did not want to be named, said: "I've followed Sunderland away for number of years and have never witnessed mob violence like this.
"They announced over the loud speaker that our coaches had been moved to car park B, but nobody knew where that was, so there was a lot of confusion.
"Needless to say, all the Coventry fans heard that announcement too, and our coach turned out to be right next to the railway line, and also an alleyway which they used to walk through.
"Myself and my daughter came out of the ground late after retrieving our flag and were met with a mob of Coventry yobs which had not been moved on by police.
"Running battles ensued, with violence all over the car and bus park. It was just carnage - I've never seen anything like it at any away game.
"We eventually found our bus, directly opposite the majority of Coventry fans who had gathered bricks from the train lines and pelted our supporters and buses.
"They were picking up bricks and debris from the railway line and throwing them at people. They could have killed someone.
"No arrests were made during this unbelievable act of violence. We watched from our bus as supporters were targeted.
"Even when we got back on the coach you could hear the bricks thudding off the side of it. Is this a sign of things to come in the lower leagues?"