Just like violence is at any time anywhere. Violence of any kind in any situation is upsetting. But violence in the workplace can seriously affect the emotional state of workers. Which can seriously affect productivity. Which in turn, can seriously affect business.
Employees can become too upset to work.
They can even begin missing work because of a violent incident. There are many kinds of violence in the workplace. Some very subtle and covert, but just as harmful if not more so, than overt violence. It's up to the employer to pay attention to an employee's attitude and approach. And watch for any signs that there can be trouble brewing.