No doubt, you've likely heard about yesterday's tragic shooting incident at the U.S. Holocaust Memorial Museum, where security officer Stephen T. Johns tragically lost his life.

The event is a bitter reminder about the importance of these brave men and women who serve as the "first line of defense against a terrorist attack," and the methods that can be taken to ensure their safety while on the job. All in all, there are more than 1 million private security officers in the United States - nearly twice the number of police officers.

On this morning's Today Show, the director of the U.S. Holocaust Memorial Museum, Sara Bloomfield, paid tribute to Officer Johns and commended the entire security team for their bravery and heroism:

"Everything happened yesterday as we train for these things. And as I think you've reported, two of our officers did attack this assailant and none of our visitors were hurt, so we feel that this actually worked extremely well, in terms of how many lives were saved in this incident. And again, we want to commend our officers who responded so well and pay tribute to Officer Johns, who also behaved so heroically in this incident."

As members of a union, the security officers at the Holocaust Museum are especially trained to deal with situations like the one from yesterday.

In an interview with the Center for American Progress' ThinkProgress, Steve Maritas, the organizing director of the union that represents them, said the following:

"These guys are security police professionals, which is a whole different level of training compared to security guards...When they train these guys, they're trained on more of a terrorism level."

The unfortunate incident also speaks to the need for better safety on the job. According to the Washington Post, Officer Johns did not have a protective, "bullet-proof" vest that could have aided him during the incident.