OTIS AIR NATIONAL GUARD BASE, Mass. — First responders need to be ready for anything, whether it’s a massive natural disaster or a terrorist attack.

Few know that like the emergency physicians training in Harvard’s Disaster Medicine/Emergency Management Fellowship. Two weeks ago, five of the Harvard fellows were dispatched to the Philippines to respond to Typhoon Haiyan. Just a few weeks earlier, the Harvard fellows were hosting a major terror simulation that drew lessons from the Boston Marathon bombing and other past, man-made disasters.

“The unique thing about disaster response that makes it different from almost everything else is the fact that you’re responding to a unique event — every disaster is unique, in nature and both modality and scenario and environment in which it happens,” Greg Ciottone, the director of the Harvard program, told CBSNews.com.

Ciottone was a commander of one of the first federal disaster teams on the scene at Ground Zero after the Sept. 11, 2001 terrorist attacks. While no one can predict the scenarios where first responders will be needed, disaster simulations are still crucial, he said.

“We’re forced to respond using a multitude of agencies and personnel that don’t normally work together,” he said, “so what you don’t want to have happen is have all these different agencies come together for the first time in a real live disaster event, and that’s why we conduct these drills as often as we can.”

Disaster simulations are common in the post 9/11 era, but the one that Ciottone and his team conducted at the Otis Air National Guard Base in Massachusetts was unique in its size and scope. The Harvard event brought together the National Guard, the Cambridge Police, the Massachusetts Reserve Corps, paramedics, ER physicians and others. It was coordinated to coincide with the Second Annual International Extreme Medicine Expo — hosted this year in Boston — so the participants and observers came from around the world.

The event started by applying makeup — in this case, called moulage — to 92 volunteers pretending to be victims. Kathy Cardeiro, a retired nurse from Bourne, Mass., joined the Massachusetts Reserve Corps (MRC) a couple of years ago, but the volunteer work has meant more to her since the Marathon bombing.

“I think we’ve probably learned a lot from that, how to cope and also learned a lot that people in general all want to help, whether they’re MRC, there are a lot of people that step out, and step up,” she said.

Ciottone and his team created a scenario that started with a lone shooter — a scene now all too common in the U.S. Police arrived to find more than a dozen injured. Paramedics started to arrive, but the scene was complicated by a second incident — a bomb exploding.

This kind of second attack — typically designed to target first responders — has become a common tactic around the world. It may have been what the Boston bombers intended to do with their second device.

After the explosion, there were dozens of more victims to treat, and seven of the first responders were “killed.” The remaining responders — who were not told ahead of time what the scenario would be — suddenly had to reassess the situation and shift their priorities.

“It started off almost textbookish in terms of the initial wave of responders doing their job appropriately, then it broke down a little bit when we lost that first group of responders,” said Jonathan Siegel, a paramedic and supervisor with Cataldo Ambulance Service who participated in the simulation. “The next group of responders came in and were not able to recognize that the command and control roles needed to be backfilled in order for the rest of this to run smoothly.”

After the event, Ciottone explained that the first responders spent too much time triaging and assessing each potential victim — typically the right move — except in a case like this, where quick, immediate action like applying a tourniquet can save lives. In fact, tourniquets were only recently added as standard equipment for Boston EMS, but they proved crucial on April 15.

“The amputations — we saw them the Boston Marathon,” Ciottone explained to the event participants. “The reason that only people two or three killed at the Boston Marathon were from the bombing itself and nobody else was killed, despite the fact there were 30 to 40 life threatening injuries… people jumped quickly with those tourniquets.”

Knowing when to stop to triage a victim is stressful enough, but first responders also have to think about logistics. With dozens of victims down, several ambulances were called to the scene. Ciottone explained after the fact that the scene was inspired by the 1990 Avianca plane crash, when ambulances approached the Long Island, New York crash scene on a narrow road. Once they were there, the ambulances were stuck in a bottleneck.

“We did put a couple obstacles there, they were the blasted out ambulances from the first responders,” he said. “But what we were hoping was you would actually complete that circle, realize that someone needs to get out and help maneuver and move around those obstacles. Instead, what was done, the ambulances came up and made their own route a different way, which had some pluses and minuses to it.”

In many ways, the drill went nothing like it was planned, said Mike Rubin, one of the Harvard fellows who helped organize the event — but that, in a sense, made it more realistic.

“There’s no definite protocol to follow, so you have to reinvent the wheel with every disaster to accommodate the factors,” Rubin said. “It requires some snap decisions and there’s no time to question whether you’re doing the right thing or not.”