Staying in a state of constant readiness is a necessity, for law enforcement, is an all too real reminder that people at work, at a movie or in school are facing the threat of an active shooter.
In Anne Arundel County, home to the state capital, the NSA and other structures, police there say they're ready.
"The mindset is it could be a terrorist event, it could be a multiple-target event," said Cpl. Jon Zimmer, a member of the county police's SWAT team.
When teams of officers respond to active-shooter situations, Zimmer said not only is time of the essence, but it is the literal cross-section where minutes translate to lives.
"Significant changes were made after Columbine to the mindset of our response, but it continues to tweak itself," said Zimmer.
Time has been an unfortunate teacher when it comes to lessons learned about responding to active-shooter situations. In years past, first responders were trained to wait for tactical teams to respond so they could make entry. But the evolving line of thinking is that waiting could mean that the potential for mass casualties grows exponentially. Officers now are taught to get in and neutralize a threat immediately.
For Cpl. Steven Almendez, that's new territory. Almendez has spent 14 years as a patrol officer in the county, but a growing approach to active-shooters being taught is known as the Advanced Law Enforcement Rapid Response Training, or ALERRT, which is taught to agencies and officers across the country.
ALERRT focuses on "stopping the killing," and "stopping the dying," which means Almendez is now expected to confront an active-shooter, perhaps, with little backup.
"We actually have to train ourselves, in our mind, that we're going into a situation where we could potentially be killed," he said. "Unfortunately, in our society nowadays, it's going to happen. It's happening now. So when we go out to execute our duties, even off-duty, we have to go with the mentality that this is going to happen and (we) have to be prepared."
When a husband and wife pair shot and killed 14 people at a holiday party in San Bernardino, Ca. this month, an officer who said he was nearby getting lunch responded to the scene after hearing it on his radio. That, again, is a departure from past standards, and is credited with helping to get about 50 people out of the building while the terrorists were still inside.
"Part of our training is to expose our officers to realism and stressful situations," Zimmer said. He is one of a handful of officers across the state certified to train other officers in the ALERRT curriculum, and said training takes place in empty schools and office buildings, places that, unfortunately, serve as an example of what they could actually see.
"It's a continuing improvement," Zimmer said.
And because ALERRT also focuses on "stopping the dying," in some places it means even paramedics are armed.
It's part of an evolving face of policing that Almendez said is exactly why he chose law enforcement in the first place.
"I have a wife and children. I don't want my children to grow up without a father -- and I'll say, openly, I grew up without a father and it's not a great thing -- but I will not hesitate to execute the duties of a police officer, even if it means my own life."
The Anne Arundel County Police force was among the first in the state to be trained in the ALERRT protocol. More than 70,000 officers have been trained on the technique nationwide, according to its website
It is has been adopted as the standard in nine states, including Maryland, the website reads.