In this Friday, Dec. 14, 2012 file photo provided by the Newtown Bee, Connecticut State Police lead a line of children from the Sandy Hook Elementary School in Newtown, Conn. after a shooting at the school. (AP Photo/Newtown Bee, Shannon Hicks)

Lakim Faust dressed himself in black one Friday in June, grabbed a pistol-grip shotgun and 100 rounds of ammunition and walked out the door of his apartment in Greenville, N.C. with one intention - to shoot and kill a large number of people.

The 23-year-old gunman shot his first victim, an insurance adjuster sitting in a parked car, before calmly walking across the street and shooting three others in a Wal-Mart parking lot, according to local police reports. Eventually the police shot and subdued the gunman.

Because no one died in the rampage, this incident was not classified as a mass killing and likely would have escaped deeper scrutiny. But after last year's attack at Sandy Hook Elementary School in Newtown, Conn., killed 20 students and six staff members, the FBI began studying events like these to develop new ways to respond and save lives.

Active shooters are defined by the FBI as gunmen who arrive on the scene with the specific intent to commit mass murder. Unlike other mass killings or mass shootings, this sub-set does not include incidents such as bank robberies or drug deals that may turn lethal.

According to the FBI, there is a disturbing rise in the number of "active shooter" incidents across America, like the Greenville attack. The FBI is basing its conclusion on data collected by a Texas State University researcher that was exclusively obtained by Scripps News. The data shows the number of active shooter events in the U.S. has tripled in recent years. "There is a higher number of people being shot and a higher number of people being killed," said special agent Katherine Schweit, head of the FBI's active shooter team which formed after last year's rampage in Newtown.

The data reveals that active shooters target places large and small, with most incidents going largely unnoticed outside of the immediate community. In Tulsa, Okla., in 2012, two gunmen drove around town opening fire at random African-Americans, killing three people. At Inskip Elementary School in Knoxville, Tenn. a school employee opened fire on administrators in 2010. In Lake Butler, Fla., this past August, a former trucking company employee drove around the city on a Saturday morning and shot two former co-workers and his one-time boss, killing two before arriving home, where he shot himself.

This year, recent high profile active shooting incidents include an attack at the Los Angeles International Airport where a gunman killed a Transportation Security Administration officer and wounded two other agents. In September, a gunman killed 12 people inside a heavily secured building at the Washington, D.C., Navy Yard.

The Scripps review of the active shooter data found a total of 14 attacks this year, with gunmen shooting 73 people and killing 39. Four of those incidents resulted in shootings but no fatalities. "The characteristics that bind them together unfortunately is (the) shooter's desire to kill" said Special Agent Schweit, and to kill "as many people and kill them as fast and freely as he may be able to " she said in an exclusive interview with Scripps.

The FBI's new team does not yet keep its own statistics on active shootings but has turned to information collected by outside researchers, most notably those at Texas State University in San Marcos, Texas. Dr. Peter Blair is an associate professor of criminal justice at Texas State and has been evaluating active shooter data which show an average of 5 incidents per year from 2000 to 2008. But from 2009 to the present the number rose to an average of 15 per year. Blair attributes much of the rise to events that might escape attention from other researchers.

"Most of these are the much smaller events that end, fortunately, before a lot of people are killed," said Blair. "Workplaces are the most commonly attacked places," he said.

Prior to Newtown, Blair and Texas State had already created a training academy for police officers responding to an active shooting event. The training, which focuses on rapid response techniques, include life-like scenarios where officers enter scenes with mass casualties and have to neutralize the shooter as fast as possible.

Blair said in past events, such as the 1999 shootings at Columbine High School, police would remain outside a building until a trained SWAT (Special Weapons and Tactics) team arrived on the scene. Today, he teaches police not to wait. Blair says even the lone officer on the scene needs to intervene in an attack, emphasizing that body counts can rise in an active shooting event with every passing second.

"The shooter knows that he's on the clock," said Blair "He knows people are coming for me, they're going to stop me, and I have to do as much damage as I can as quickly as I can."

Another resource the FBI has looked to, is research on mass casualties from Dr. John Nicoletti, an expert in workplace and school violence based in Lakewood, Colo. Nicoletti found 74 percent of those events last year took place with the assailant walking in the main entrance.

Nicoletti also found that the majority of attackers were insiders, or people that were known by their victims. According to Nicoletti's research, the majority of attackers openly talk about their strikes before they happen and he believes that makes many attacks preventable.

"You shouldn't have an attack from an insider in this day and age," he said. "What they do is they broadcast before they attack. They tell you what they are about to do either on their websites or some way." It's what Nicoletti calls 'the thrill of the thought.' "I mean what fun would it be to be an avenger if folks didn't know you were coming to get them?" he said.

Nicoletti warns there is a big difference in risk between an unhappy worker who threatens a lawsuit against his or her employer, and someone who talks openly about some type of violence.

"As long as they're suing you they won't be shooting you," he said. "If they lose, the risk factor goes up. The risk for attack behavior goes down if they are going to the media or court."

Both Nicoletti and Blair have also studied past incidents to look for what civilians can do to maximize chances of survival during an active shooter incident. Escaping the building as fast as possible is the best option. But if escape is not possible, both advise getting behind a locked door, or creating a barricade that would be difficult for a shooter to penetrate.

"If you look at all the shootings, in all the years, in all the locations, they've never taken time to kick down or shoot through a locked door," Nicoletti said. Blair urges reforms in the manner in which schools are constructed.

"We designed schools for fire. We designed exits and ways to get out. And we haven't had any school children killed in fire incidents in the last 50 years in schools," he said. "We've had a lot of kids killed in active shooter events. We ought to be looking at how do we design schools to facilitate survival."

Some respected criminologists caution that the apparent rise in active shooter events, may not in fact be real.

"I'd be hesitant to declare trends based off a modest number of years and a modest amount of data," said Dr. James Alan Fox of Northeastern University, an expert in mass shootings who served on President Clinton's advisory panel on school shootings. Fox warns that researchers may have a difficult time finding older cases. "The question is in 2003, are you sure that all those cases that would today be called active shooters would have been locatable," said Fox. According to Fox's own research, the number of "mass killings" has stayed relatively flat over the last 35 years.

The FBI's active shooter team concedes it has plenty of room to grow in understanding the events themselves. But they are not waiting for all of the answers before taking action. This year, the team has trained more than 1,300 law enforcement officers who represent more than 500 police departments across the nation. In addition, this year the FBI has met with nearly 10,000 commanders and leaders of law enforcement agencies to share best practices and lessons learned.

FBI agent Schweit says this free training is critically important because many active shooter events happen in smaller communities with police departments that often have 20 or fewer officers on staff.

Next year, the FBI plans to expand its training focus to include helping get paramedics into a "warm" or even "hot zone," where a shooter might still be active. Schweit says "That's new, because we know it saves lives."