According to BBC Football, the incident occurred in the 72nd minute of the match when Bielik went to retrieve a ball from the stands. A fan threw a ball at the head of Cardiff defender Perry Ng, resulting in both fans being ejected from the stadium. No players were booked during the incident.
Mousinho has expressed his disappointment with the incident, stating that it was "not good" and that the club cannot have such behaviour at Fratton Park. He has extended an apology to the players and Cardiff City, promising to try and cut out such incidents in the future. The Portsmouth head coach wants to create a difficult atmosphere at Fratton Park, but understands that it should not tip over into violence.
Cardiff head coach Brian Barry-Murphy has also spoken out about the incident, describing it as "not acceptable". He praised the officials for their handling of the situation and expressed his focus on protecting the players and making sure they play well and win. The incident is likely to be looked at by the Football Association and the club, with a process to be implemented to prevent such incidents in the future.
The next step will be for the Football Association to investigate the incident and implement any necessary measures to prevent similar incidents from happening in the future.