A football club has reminded fans that flares are not allowed at matches after a girl was struck by one and a person was arrested on Saturday.
Oxford United said three fans have been arrested for using flares at their games in less than three months.
It said each of them faced a lengthy ban and a criminal record.
The club said pictures from CCTV, along with social media, fans' cameras and TV images, mean those responsible are "almost always" identified.
The U's said a person was arrested at its Carabao Cup tie against Crystal Palace at the Kassam Stadium on 23 August.