Colorado investigators still aren't certain how Duane Morrison, carrying two guns, managed to get into Platte Canyon High School near Denver Wednesday and take students hostage in a second-floor classroom.
A three-hour standoff ended when a SWAT team stormed in after sheriff Fred Wegener learned that Morrison was sexually assaulting the female hostages.
"That's why I made the decision to go and save them," Wegener says.
Just before killing himself, officials say, Morrison shot 16-year-old Emily Keyes, who died a short time later.
"She was her parents' daughter, but everybody that knew her loved her. And so it's a loss for the entire community," says Bobbie Sterling, a friend of Keyes.
The shooting represents one of the least common school threats. Attacks by outsiders who have no connection to students or teachers account for about two percent of fatal school shootings.
Since Columbine shocked the nation seven years ago, schools nationwide have become far more serious about security. Key improvements, safety exerts say, include watching for victims of bullying who could turn violent, and encouraging students to report threats.
"Schools have been much better at detecting crime before it occurs," says Ronald Stephens, a school safety expert. "There's more tip lines out there. There's a closer working partnership with law enforcement. Mental health professionals are now working much closer with educators. So it's been a team effort."
Police in Green Bay, Wis., credit a friend's tip earlier this month with stopping two classmates from shooting up a high school. And in Kansas, authorities say the discovery of an Internet threat prevented a similar attack last spring.
During the past 14 years, the number of fatal shootings at the nation's schools has dropped sharply. Attacks like the one Wednesday in Bailey, Colo. — by outsiders, not students — account for only two percent of those deaths.
Schools are more practiced now at ordering lockdowns, like the one near Tampa, Fla., Thursday, with a shooting suspect on the loose nearby. But some security consultants say safety is no longer the priority it was.
"In the weeks and months after Columbine, school safety improved greatly, but that progress has actually stalled and is slipping backwards a great deal now," says Kenneth Trump, a school safety consultant.
Parents in Las Vegas, for example, are pushing for more police in schools, after a string of incidents involving guns.
And the Justice Department says just under half of students surveyed say their schools still don't lock entrance doors during the day.