ONTARIO >> In one of many scenarios, an “armed man” ran into an unused terminal at L.A./Ontario International Airport on Saturday, “shooting” three people before officers swooped in to save the day.

The exercise allowed officers to do live training in the event a real-life, or active, shooter scenario plays out.

“There are many places where we can conduct this type of training,” said one of the SWAT officers, who didn’t want his name released. “But if we can take advantage of training as if it were real, then we have to opportunity to save more lives in a live scenario.”

Nearly 300 sworn members of the Los Angeles Airport Police Department and the Los Angeles Police Department took part in the training, said an airport police spokeswoman, Sgt. Belinda Nettles.

“Many resources were pulled together to make this training happen,” Nettles said. “In the event that something similar to this were to ever happen, it’s vital that we train this way so everyone knows what to do in order to save lives.”

Some people stood at the corner of Airport Way and Vineyard Avenue to watch the scenarios play out.

“I think they should train everywhere they can to become the most proficient police agency around in order to protect us,” said Ontario resident Margie Hamilton. “If I ever need to be saved, I want the cops that are highly skilled in this type of rescue to be there for me.”

The Department of Homeland Security has defined an active shooter as “an individual actively engaged in killing or attempting to kill people in a conﬁned and populated area; in most cases, active shooters use ﬁrearms and there is no pattern or method to their selection of victims.”

Over the last year, there have been several incidents where an active shooter has gone into a business or school and killed for no apparent reason, including the DC Navy Yard and Sandy Hook Elementary school in Newtown, Conn.

Another officer who didn’t want his name disclosed spoke of the tragedies that most of the world watched live on network television.

“Without constant training we aren’t effective enough to work and communicate as a team,” the officer said, “which is desperately needed so we don’t have the next Sandy Hook.”