Northern Ireland fans of Manchester United were caught up in the violence which marred Wednesday night's Champions League match against Roma.
Manchester United fans and police clashed during the game
There were clashes outside the ground and more trouble inside, with visiting supporters claiming that they were attacked with batons by Italian police.
BBC NI journalist Joel Taggart said he was punched to the ground by a Roma fan as he approached the ticket gate.
He said police also "took out" fans indiscriminately inside the ground.
He said three other fans he talked to entering the ground said they had been ambushed by Roma "ultra" fans, one of them being hit with a miniature baton.
Mr Taggart said the clashes with police happened after Roma scored their first goal and their fans started to taunt United fans on the other side of a perspex partition.
"I can only assume that the police felt there was a chance they were going to force their way through the fence and they just stormed down the stairwell on the United side of the fence knocking people over, basically trying to get in between the two sides," he said.
This then "provoked a response" among the United fans, Mr Taggart said.
"There was then 10 or 15 minutes of the police trying to regain ground and they just indiscriminately took out anybody who was in their way," he said.
"It was good fortune that we weren't in that particular area of the ground - we saw women being beaten out of the way, there were men, children - whoever was there was knocked out of the way."
He said some United fans then started fighting with the police - some throwing chairs - leading to about 10 minutes of sustained clashes.
This Northern Irish Utd fan said he was hit with a police baton while helping a female supporter
Mr Taggart said missiles had also been thrown by both sets of fans during the game, and the whole incident had been very frightening.
"It was so indiscriminate, I think that was the most frightening thing," he said.
"It sort of edged closer and closer towards you and you feared even a crush situation because the people who started the game standing in the stairwells, standing in the aisles, had absolutely nowhere to go."
Another Northern Irish fan at the match said he was hit on the head with a police baton while trying to help a female fan.
He also accused the police of indiscriminate attacks.
Rome police said 18 United fans and two Roma fans needed medical treatment as a result of incidents inside and outside the stadium.
The city's head of police, Achille Serra, insisted the police action was a "justified response", and said there would be no inquiry unless he was shown evidence of any alleged police brutality.
UEFA has announced they will launch an investigation into the night's events.
Before the game Manchester United fans were warned in letters and on the club's website to avoid certain areas of the city as they could be attacked by Roma's hardcore "ultra" fans.
Three Middlesbrough fans were stabbed and 10 others hurt during fights with Roma fans at an Uefa Cup quarter-final last year.