Sunderland fans have criticised West Midlands Police over the trouble which flared after the away game at Coventry City.
Supporters from both sides were involved in a brawl outside the Ricoh Arena, after yesterday's televised 1-1 draw.
Reports on social media said Coventry fans surged towards the barriers separating the two sets of supporters, and some of the Sunderland contingent responded.
There were also reports of the fleet of coaches which were waiting for Sunderland supporters outside the away end being pelted with rocks.
It is believed the game was classed as Category A-, which means it wasn't a high risk fixture, even though Sunderland had the backing of 5,000 fans.
Some messages on social media blame Sunderland fans for inciting the trouble, for apparently threatening to damage a statue of Coventry legend Jimmy Hill.
The late club chairman was unpopular with older supporters, who blamed him for their relegation from Division One in 1977.
But many others say the West Midlands Police were to blame for yesterday's ugly scenes for not employing a 'holdback' policy, of allowing home fans to disperse before letting the visitors out.
Chris O' Neill (@sneillybones) tweeted: "What the hell happened today at the end of the game? Who was the bright spark that made the decision to bring all the away coaches over to car park B, right next to where the Coventry fans exit the stadium? Absolute madness."
Cornelius the 2nd, who declared himself a neutral fan of neither club, posted: "Just watched it all kick off between Coventry and Sunderland fans. Never seen anything like that - 70/80s stuff. Outrageous."
Sky Blue Hub (@SkyCcfc): "Tannoy announcements during the game clearly telling fans that Sunderland transport home would be picking up right behind away end. Green light for any troublemakers."
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Carol Atkins (@carolatkins2): "It was a really stupid decision letting both (sets of) fans out at same time. We got stuck In the middle of it all with my granddaughter. Policing today was a joke."
She added: "The worst one was the Sunderland dad who had took his lad for his first awayday and had parked by the casino. Asked which way to go when he came out and was pointed right into all the trouble. Poor lad was terrified!"
Steve Strong (@swadsteve): "I had to meet my stepdad outside, who's a Sunderland fan, and we both had to walk right into that brawl. I ended up pulling him away from the trouble when I seen him walking through the middle of it. The police were too busy shouting at people to notice what was going off."
Keelan Murray (@keelanmurray1): "Absolute hell on outside the ground. Coventry fans boxing Sunderland fans in throwing bricks and all sorts. Shocking by the police."
Sunderland supporter Lewis H (@lawis_h__) tweeted: "Coventry fans started throwing rocks off the buses and fans after they (?) the barrier as we came out the stadium."
Simon Hetherington: "It was ridiculous, funnelling fans into one small space to get towards the train station at the side of the coaches. Right where all the bother was happening."
Nick Robbo (@Nick_Robbo90): "If away fans were held back so home fans could disperse it would be effective in preventing trouble. Shocking to allow the Sunderland fans leave at the same time as City fans."
Leighann Brooks (@leighann100169): "There should have been large screens up instead of just the barriers (like the crash ones they used on motorways) that way there would have been no goading from either side. Disgusting behaviour."
West Midlands Police said one supporter from Sunderland was arrested for being drunk and disorderly.