Four people were arrested in connection with an alleged assault on jockey Aidan Coleman at Southwell racecourse on Tuesday afternoon.
The incident occurred after the last race on the card at 5.10pm, the Book Christmas At Southwell Racecourse Mares' Novices' Hurdle, in which Coleman finished last aboard Sawwala.
Nottinghamshire Police said in a statement two men and one woman were arrested on suspicion of assault and criminal damage, with another woman arrested on suspicion of obstructing police.
Coleman sustained "minor injuries" and is understood to have returned home after the incident.
A statement issued by Nottinghamshire Police read: "Four people have been arrested following an assault at Southwell racecourse this afternoon.
"Officers were called at 5.23pm to reports of a man being assaulted in the weighing room.
"They attended and arrested two men and one woman on suspicion of assault and criminal damage, and another woman for obstructing police.
"The victim sustained minor injuries.
"If you saw anything please call Nottinghamshire Police on 101, quoting incident 651 on the incident of September 29."
Southwell stewards said in a statement that two racegoers gained entrance into the jockeys' changing room, with the incident referred to the British Horseracing Authority.
A stewards' report read: "The stewards held an inquiry into the circumstances surrounding an incident which occurred after the last race in the jockeys' changing rooms after two members of the public gained access, and during which a jockey sustained minor injuries.
"They interviewed jockeys Aidan Coleman, Adam Pogson and Tom Scudamore, two of the jockeys' valets, a racecourse medical officer, the clerk of the Course and two members of the racecourse executive.
"Having heard their evidence, the stewards passed the matter to the BHA for further consideration."