A smoke bomb was set off as Luton and Watford footballers observed a minute’s silence in memory of the Duke of Edinburgh on Saturday.
The incident happened inside Luton's stadium Kenilworth Road on Saturday afternoon.
English Football League (EFL) games were moved from their traditional 3pm kick-off slot due to Prince Philip’s funeral taking place at St George’s Chapel in Windsor Castle at the same time following his death last week at the age of 99.
As Luton and Watford players stood around the centre circle for a minute’s silence before the 12.30pm start, a smoke bomb was let off inside the ground close to the executive boxes and seating.
No players were near to the device when it exploded to reveal red smoke, but an image of it could be seen on a picture taken by Luton’s official Twitter account.
Watch: Raucous protesters chant ‘kill the bill!’ on day of Prince Philip's funeral
Due to the coronavirus pandemic, all EFL matches continue to be played behind closed doors, but it did not stop a slight disruption ahead of the derby fixture in the Sky Bet Championship, with a steward forced to dispose of the smoke bomb before play was able to get underway.
The Royal Family paid their last respects to Prince Philip on Saturday at a funeral that celebrated his naval past, international heritage, and seven decades of service.
The Queen, dressed in black and a white trimmed black mask, stood alone as the funeral service began in St George's Chapel, dating back to 1475.
At the ceremony in Windsor Castle, mourners, including Prince Charles and his sons Princes William and Harry, were limited in number and separated due to COVID-19 rules.
After the nation observed a minute's silence, Harry and William took up their places on opposite sides of the chapel with the final resting place of Tudor monarch Henry VIII dividing them.
Before the procession, military bands spaced out across the quadrangle of Windsor Castle to play the prince's chosen music, including I Vow To Thee My Country, Jerusalem and Nimrod.
Watch: Prince Philip's funeral to take place 'entirely inside' Windsor Castle grounds