This morning, authorities say, as many as two gunmen converged on the Washington Navy Yard, killing at least four people and wounding many others. The Washington Post's liveblog is providing up-to-the-minute coverage of the events. For a bit of context, I spoke with a former member of the Air Force with experience in base security. For reasons related to his current job, he asked to remain anonymous.

Police respond to the report of a shooting at the Navy Yard in Southeast Washington, D.C. (Saul Loeb / AFP/Getty Images)

Ezra Klein: What’s your background in military security?

I am a former active duty Air Force member. I did seven years active duty. I was a member of the Air Force Security Forces, which is the Air Force equivalent of military police. So, day-to-day, we were responsible for base security and law security.

EK: What should people know about the kind of base that we’re dealing with at the Navy Yard?

This base in particular is largely civilian. It’s primarily an acquisition and logistics support base. All the interviews you’re seeing with people in the building, to date, they’ve all been civilians. So that’s the biggest thing here. The vision people have of a military base with uniformed military marching around, that’s not what the Navy Yard is.

EK: Does that mean the law enforcement is provided by civilians, too? Or is this a situation where the base is civilian but the security is provided by the military? 

No, it’s split. There’s a civilian police presence on base. They make up the majority of the response force. There is active-duty navy personnel who work with them. If you’re coming on base you get your ID checked by a Navy master-of-arms or a civilian police officer.

EK: I think one thing people assume when they see this kind of violence break out on military bases is that these bases are bristling with weapons, that the shooter is going into a space where everyone else is armed, too. Is that true?

No, absolutely not. I would guess the Navy Yard -- and I don’t have direct affiliation with the law enforcement unit of the base -- but I would guess there are two armories on the Yard. One for base law enforcement and one for a ceremonial drill team, though that one is likely just drill weapons. So my guess is no more than a couple of dozen weapons on the Navy Yard.

EK: How different is that from a more traditional military base?

At a more traditional military base staffed by military units getting ready to deploy, you’d have an armory associated with every large unit that drew weapons and went out to the field to drill. So for those kinds of bases there would be more guns. But even though there are so many more weapons, just because the weapons are there, they don’t just start handing out weapons at the armory when these things happen. It’s still treated as a law enforcement response. The only people who respond would be those tasked with law enforcement. Now that can expand in a situation with live gunmen, and it has here. But in general, nobody carries guns on base save for those actively training and the law enforcement.

EK: How hard is it to get into one of these bases?

There’s been a lot of talk of how did somebody get a gun on base? That’s silly. There are thousands of cars in and out. It’s not like going into the airport to get on base. You show your common access card, which is handed out to every DoD employee and most contractors who work on base, as well. All you do is show that, and you’re let on base. As a general rule your vehicle isn’t searched or anything else. It’s the integrity of the individual person that keeps them from bringing guns with them onto the base.

EK: That assumes these shooters already had access, though. What if you don’t have a CAC card?

If you were a random D.C. resident and you pulled up to the gate and you tried to show your driver’s license, you’d be sent to the visitor’s center; you’d have to go inside, you’d have to say who you were there to visit, and you basically need to be sponsored onto the base. If you wanted to bring your vehicle on with you, it gets even more in-depth, looking into your license information and so on. But it’s all routine. Your vehicle isn’t completely inspected. It’s not a huge process.

EK: Watching the coverage, is there anything, aside from the basic horror of it, that you’ve noticed about the attack?

This is horrible, and I don’t want to diminish it. But my feeling all morning was that this was a disgruntled employee or interpersonal conflict. The fact that there are [reportedly at the time] two shooters raises more questions. But Navy Yard is a very odd target if you’re thinking about terrorism. The idea of going onto a military base that’s largely staffed with civilians and going into a largely civilian facility on that base seems odd when you’re in a city like D.C. with so many other symbolic targets.