Earlier this week, a tragic ending to an employee termination occurred at a private school in Jacksonville, Florida, when a just-fired teacher returned to the school and shot the head of the school and then himself. The gunman, Shane Schumerth, was a Spanish teacher at the school.

It appears that the firing meeting took place away from students and with a witness. The terminated teacher was then escorted off campus; security was informed and a guard was placed at the school’s entrance.

The school had a full time Director of Safety and Security, and implemented security measures such as video surveillance, security gates and a digital patrol system that ensured required safety patrols were completed each day.

However, the former teacher was able to gain access to the administrator’s office by going through the football field. He carried an AK-47 semi-automatic assault rifle and nearly 100 rounds of ammunition in a guitar case.

Officials say this sort of tragedy cannot be prevented—especially when the individual gives no warning, and is determined to hurt someone. This school did all the right things: badges are required of all visitors; classroom cameras, intercoms and panic buttons are connected to the main office; gates are closed and locked at night.

Still, while a random act of violence can’t be prevented, a tragedy like this is a wake-up call for all employers. Termination procedures should include notification to all staff that the fired employee is no longer allowed on site, as well as instructions on what to do if he or she is seen on the premises.

Security badges must be deactivated immediately. Managers should pay extra attention, and be extra sensitive, to any unstable or unusual behavior by an employee before, during or after the termination process. If they feel the employee could be a threat, everyone should be notified so they can be on guard.

And don’t wait until termination to deal with an unstable or threatening employee. Suspending the person while an investigation takes place is always an option.

Be sure that hiring procedures include thorough pre-employment screening. It’s vital to know who you’re hiring, and to screen potential employees for past criminal activity, felony convictions, sex offenses and work history.

Reports are surfacing that the professor charged with the fatal shooting of three colleagues last week in Alabama had a violent history that perhaps could have been discovered—with more thorough background screening.

Amy Bishop, who also wounded three others, had more than one incident in her criminal past. She was arrested in 2002 for assaulting a woman in a pancake restaurant—over a child’s booster seat. She shot and killed her brother in 1986, in what was officially ruled an accident. And she was questioned about a mail bomb received by her supervisor at Harvard.

The question remains: was this information available, and not acted upon by the University? Or did the University of Alabama use an insufficient level of pre employment screening for Amy Bishop’s position?

Employers typically choose from several levesl of background screening. The lowest level might be enough for a back office employee with no client contact, on-the-job driving, or access to sensitive data. On the other hand, day care providers and nursing homes, who work with vulnerable populations, need all the information they can get on a potential hire.

Why not the University of Alabama? Isn’t it better to know more, rather than less, information on a university professor, who is in a position of power and influence over students?

Now that the damage has been done, and the victims’ families face untold grief and loss, it is easy to look back and wish things had been done differently. Instead of regretting inaction, isn’t it better to take all possible actions—before workplace violence occurs?