Fans caught up in trouble at a football match in Plymouth have blamed a "low-key" approach by police.
At least 20 people were arrested on Tuesday evening at the first Devon derby between Plymouth Argyle and Exeter City for more than eight years.
Violence broke out in the stands during the game, a steward was injured and visiting fans were attacked as they tried to leave Home Park stadium.
Devon and Cornwall Police said their resources were used "to good effect".
Radio Devon sports presenter James Vickery, who was at the match as a spectator, said the level of violence was "absolutely terrifying".
He was told by a steward to cover up his football "colours" during the trouble.
An Exeter fan, who asked not to be identified, said: "There were no police outside the ground and people were being chased, cars were being bricked and a coach window was bricked.
"I feel badly let down by the police."
Both Plymouth Argyle and Exeter City's supporters' clubs condemned the level of policing at the match.
Argyle supporters' club chairman David Marshall said there should have been a high-profile police presence.
"They knew there was about 2,000 Exeter fans coming, so it was a bad decision," he said.
Mr Marshall also criticised the violent behaviour of some fans.
"It was totally disgraceful - everyone wants to enjoy the football, but there's obviously a small element who want to misbehave," he said.
Dave Bennett, the vice chairman of Exeter City's supporters' club, said any derby game between the two Devon sides should be treated as high risk.
"I blame the trouble on the people who caused it, but it's very obvious the police clearly got it totally wrong," he said.
"It was the first derby game for years, they knew the number of supporters to expect and they could have seen the comments on the club forums."
Supt Dave Sumner said there were more than 60 officers at the match, but "disgraceful" behaviour by a minority of fans put police and stewards under intense pressure.
Bottles, fireworks and coins were thrown at police and stewards and one steward was knocked unconscious and kicked as he lay on the ground.
"It was the sort of behaviour that hasn't been seen at Home Park or many other grounds for several years and it took some significant dealing with, both during the game and after the match," Supt Sumner said.
He said tension between the fans began rising in the second half and the focus was to keep them apart.
"Our bottom line was to stop a breach of the segregation line and that was prevented," he said.
Supt Sumner said the segregation of fans would have continued outside the stadium if officers and stewards had not had to deal with serious trouble shortly before the final whistle.
"The fact is the resources were there and they were used to effect, but we can't be everywhere," said.
Plymouth Argyle said it was "totally satisfied" with its stewarding and the police operation, despite "extreme provocation from a few people".
Police and club officials are to study CCTV footage and action, including issuing banning orders - will be taken against offenders, the club added.
Exeter City won the Johnstone's Paint Trophy Southern Area tie 2-1, with a last-minute goal.
The two sides are due to meet again in League One on 11 December, but as a result of Tuesday's violence, Mr Sumner said policing levels would be higher.