SEATTLE - It's a grim fact of life today that colleges across the country are under a constant state of vigilance, prepared to go into emergency mode if a shooter begins firing bullets on campus, as happened at Seattle Pacific University this week.
But although it may seem like such shootings are on the increase, they are sporadic and relatively rare, experts say.
"Campus violent crimes are more rare than in the general population among that age group. But certainly, it's a great tragedy when it happens on campus," said Chris Blake, chief staff officer for the International Association of Campus Law Enforcement Administrators.
A federal law in place since the Virginia Tech massacre of 2007 requires colleges to create notification systems that can alert the entire campus community when there is an emergency.
Colleges and universities have invested in systems that can deliver text messages, send alerts through Twitter and Facebook, take over the screens of every networked computer on campus, sound indoor and outdoor alarms and even lock building doors remotely.
"You can never be fast enough," said University of Washington spokesman Norm Arkans. "Speed matters, and reliability of the system matters."
The SPU shooting happened less than two weeks after a 22-year-old man went on a deadly rampage near the campus of the University of California, Santa Barbara. He killed six students before taking his own life.
The worst mass shooting in U.S. history took place on a college campus, in April 2007, when a lone student gunman at Virginia Tech shot and killed 32 students and faculty members before killing himself. Later, Virginia Tech was sharply criticized for failing to alert students immediately that a shooting had taken place.
The federal Cleary Act, a campus crime-reporting law, was amended in 2007 to require all colleges to have an emergency notification system, although it does not specify the type of system that must be used to alert the campus community.
Many colleges and universities have installed sophisticated, redundant systems that use a variety of methods to reach everyone at once.
At SPU on Thursday afternoon, after shots were fired, a message was sent out campuswide via cellphone texts and emails, alerting to students and faculty to the shooting.
"Emergency! A campus lockdown has been initiated. This is not a drill," the first email read.
Clocks throughout the campus began beeping and flashing the word "lockdown" in red letters. Doors locked automatically. Students across campus crouched underneath desks, terrified, while digital information about the crisis played out in real time on their phones.
In a news conference Thursday night, Seattle police praised the university's quick response.
"The shooter," said Arkans, "is everyone's worst nightmare."