Bristol police injured in City v Rovers pitch invasion
Three police officers were injured when rival football fans invaded the pitch at the end of a cup match.
Supporters rushed on to the pitch at the end of a Johnstone's Paint Trophy tie between Bristol City and Bristol Rovers.
A total of 19 people were arrested as mounted police and officers in riot gear kept fans apart.
The Football Association (FA) said it was "looking into" the circumstances surrounding the pitch invasion.
A spokesman said the referee's match report had mentioned three separate incursions on to the pitch including the mass invasion at the end of the game.
The FA has now written to Bristol City asking the club for its observations and is awaiting a report from a crowd control advisor who was at the match.
It was the first derby between City and Rovers in seven years and tensions were high from the outset.
The managers of both clubs criticised the actions of some fans at City's Ashton Gate ground.
City manager Sean O'Driscoll said afterwards: "It was great up until the final whistle. The scenes at the end were disgraceful.
"You'd think we'd got promoted to the Championship and not the second round of the Johnstone's Paint Trophy."
A statement from the club said: "Actions from the minority of the near 18,000 crowd has thrust the club into the national media's eye for the wrong reasons."
Rovers boss John Ward said: "It's ridiculous that [supporters] come on the pitch and goad opposition fans. Why people can't behave themselves at a football match is beyond me."
Police in riot gear and stewards were used to keep rival fans apart in the stands during the game.
An Avon and Somerset Police spokesperson said: "There had been a perfect build-up to the game with both sets of fans well behaved and in good humour.
"But as fans began to enter the stadium small isolated pockets of anti-social behaviour broke out in and around the city and outside the ground.
"Known hooligans attached to both clubs were identified and arrests were made."
City beat Rovers 2-1 to reach the second round of the competition.