Apart from the issue of right to strike, it is extremely poor practice to "fire" someone on the spot, without any kind of investigation or disciplinary interview or hearing. You might well find that should such an incident go to tribunal here in the UK, the haste of management to sack workers without giving them the chance to state their case would result in a hefty damages award against the company, simply for failing to discipline employees fairly.
It is good practice to show at the very least a history of events for which the person is being disciplined, at the most, if the incident is gross misconduct resulting in dismissal, evidence of a proper investigation and MOST IMPORTANT of all, to show that discipline was not carried out in the heat of the moment, when both parties are angry.
Sacking someone on the spot is a foolish, irrational action that will inevitably be condemned and punished in the employment courts. So you cannot afford to be so hasty.