INDIANAPOLIS (AP) - A deadly shooting at an Indiana grocery store this week could have been much worse if not for the quick actions of two police officers who relied on training that has become commonplace since the 1999 Columbine shootings.
Cody Skipper and Jason Tripp arrived at the Elkhart store within three minutes and needed less than 60 seconds to fatally shoot a gunman who had killed two people and was threatening a third.
But experts still disagree whether patrol officers should confront a shooter immediately or wait for backup, especially if an officer is alone.
A decade ago, the Indiana officers might have waited for a specially equipped SWAT team, which was standard practice in many police departments across the country. Training for active-shooter situations has now become routine, including preparing for the possibility that lone officers could be sent to stop a rampage.
"If someone in the building is shooting, and you're the first one there, you're going in," said Indiana State Police Trooper Aaron Gaul, who trains officers from around the state.
Many security and law-enforcement professionals agree that quicker responses are needed as shootings happen more frequently.
The nation averaged five active-shooter situations annually between 2000 and 2008. Since 2009, that number has tripled, according to U.S. Attorney General Eric Holder.
But questions linger over whether a solitary officer should act as a lone ranger and go in without help.
"The rule of thumb is never to go in alone. It's a suicide mission if you go by yourself everywhere," said Texas-based security consultant Chris Grollnek, a former police officer and Marine who now trains businesses and other organizations how to respond to active shooters.
The push toward faster responses grew out of the Columbine attack. When that massacre began, a school security officer was on the scene within minutes, but police waited outside for about 40 minutes before a SWAT team arrived.
At Columbine, the shooters "had free rein of the school," said J. Pete Blair, a professor at Texas State University who helps develop police training. "And that's where the soul searching began. When someone's in there, you really need to get in there and stop the shooting."
At the Indiana Police Academy, where about 90 percent of Indiana's police officers - including Elkhart's - are trained, rookie officers receive classroom instruction on active shootings. Officers with a year or more of experience can opt for more advanced training that includes a mock scenario at a vacant school building.
Lone officers are trained to "go straight in" with a protective vest if possible and approach the sound of shooting stealthily, using as much cover as possible, said Capt. David Younce, who handles such training at the academy in Plainfield, just west of Indianapolis.
"There's no fine line that says you have to wait for backup," Younce said.
While the ideal tactic is to gather a team of four or five officers, that isn't always possible, Blair said.
Even stopping to help victims is out of the question.
"If we stop and try to treat and help every person, we're losing seconds where seconds can cost lives," Indiana State Police Sgt. Trent Smith said.
Smith said the Elkhart officers followed that protocol.
"They went in in a professional pattern and strategically cleared that store in a matter of seconds," Smith said.
Ultimately, the first officer on the scene must pick the best course of action to prevent deaths.
"Our goal is to get in there and stop that aggressive act, whatever it is or whatever that person is doing, absolutely as fast as possible," Smith said. "We don't wait to take the time for other people to be backup."
Associated Press Writer Tom Coyne in South Bend contributed to this report.