Two words that would trigger alarm in anyone ring across the police radio.
Within minutes, a SWAT team is on the scene. A dispatcher relays that a subject has been shot and is in custody. Actors playing the role of victims are carried to a triage area with markings of wounds.
It seems all too real, but it's a drill.
"It is still very scary, extremely intense," said Christine Zelaya, principal at Sycamore Trails Elementary School in Bartlett. She participated in Elgin Area School District U-46's active shooter training last summer. "It is frightening, even knowing it's a drill. It is frightening, but very valuable."
For children across the country growing up in the shadow of shootings like those at Columbine High School in Colorado and Sandy Hook Elementary School in Connecticut, lockdown exercises have become a fixture -- the new fire drill. When they're called, teachers are trained to turn off the lights, lock the doors, and hide students quietly behind bookshelves, into corners or closets -- out of harm's way.
"Kids in our system don't know school without those kinds of drills," said Bob Ross, assistant superintendent for secondary education for Naperville Unit District 203.
But today even lockdowns seem inadequate. Today, many districts have adopted "active shooter drills," which include role-playing shooters and victims in the school building.
Last summer Gov. Pat Quinn signed a law requiring all Illinois school districts to hold at least one drill each school year that includes a shooting and law enforcement participation. The drill must take place in a school.
For many suburban school districts, that requirement falls in line with drills they already have in place -- but there is debate about whether they should take place when kids are present.
Those who argue in favor say students need to be trained, their vulnerabilities tested, and that the focus must be on preparation.
Others, though, worry about the emotional trauma potentially inflicted on children hearing gunshots in school -- drill or no drill.
U-46 has conducted active shooter exercises in coordination with the Elgin police during the summer since 2007, with other law enforcement agencies and fire departments invited in. The simulation, done when students are not present, includes a shooting situation, mock injuries, lockdown, rapid police deployment and "reunification" at another location.
"The focus is how to get officers to the building, in the building, and to take on the active shooter as fast as possible," said John Heiderscheidt, the district's safety and security coordinator.
Naperville Central High School hosted an active shooter training exercise during winter break, and a Naperville elementary school had one when school was out in January. Similarly, Barrington Unit District 220 has held them during breaks and Glenbard High School District 87 hosted a violent intruder drill for staff on an institute day two weeks ago.
No children were included in those, but other districts have chosen to conduct training while school is in session.
In recent years, Maine South High School and the Park Ridge police and fire departments conducted an active shooter drill on a regular school day, with students present; students, parents and the Park Ridge community were notified in advance that it was just a drill. Adult actors played a shooter and two hostages, and police sent in a rapid response team.
"I would say there was very good cooperation by everyone involved," said David Beery, a spokesman for the district. "It was generally well-received, and viewed for what it is, which is a way to prepare for a possible situation which everyone hopes never occurs."
At Cary-Grove High School, however, a controversial "code red lockdown drill" in January 2013 alarmed some parents and mental health professionals. They questioned whether the sound of gunshots ringing in the hallways during school would generate more paranoia than benefit.
Barrington District 220 has not yet crossed the line of including students in active shooter training.
"It is a challenging, and a hot topic, the idea of having the noise of the guns with students in school and thinking of their social and emotional well-being," said Austin Johnson, District 220's safety coordinator. "Do we want to bring that stress upon them? It is something being contemplated by a number of districts, trying to decide what is best."
Palatine-Schaumburg High School District 211, which conducts a lockdown drill each semester, held "comprehensive" active shooter training on an institute day last school year at both Palatine and Schaumburg high schools. Staff were involved on all levels, including cafeteria and support staff. "Simulated" classrooms were set up. Police fired several rounds of blanks and some classrooms were evacuated during the roughly three-hour exercise.
No kids, however, were included, and Associate Superintendent Dan Cates doesn't anticipate going in that direction in the future.
"We're always mindful of the impact on students on all fronts," Cates said. "When looking at the potential risk and trauma and upsetting features that would occur if kids were present, we felt that particular level of intensity was most helpful for staff and students if conducted without students."
Principal Zelaya, who has three children of her own, draws a line on the debate: It depends on a student's age.
"Putting that parent hat on, I do think the drill is a good experience in this day and age for older, high school-age kids," she said, "(but) I don't think that's something I would ever want to expose elementary-age kids to. That would be very traumatizing."
In Libertyville-Vernon Hills Area High School District 128, active shooter drills were done at each of its high schools in the fall with staff and students present.
"The drills are as much for students and staff as they are for law enforcement," district spokeswoman Mary Todoric said. "The drills help students and staff be prepared."
Lake Zurich Unit District 95 does lockdown drills supervised by the police or fire department. It has not yet had active shooter exercises, but intends to. District staff did observe such a drill at Carmel Catholic High School in Mundelein in recent years.
"I would imagine we might have that conversation (of whether to include students in the drill)," said district spokeswoman Jean Malek. "I think there is a certain amount that is appropriate and certain amount that is not."
The specter of a potential violent intruder is present in many perceived "safe" suburban communities like Lake Zurich, even in cases where there was no malicious intent or direct threat to a school.
This past December, a boy believed to have an unspecified weapon inside Lake Zurich Middle School South caused a lockdown there and at Isaac Fox Elementary School.
Steeple Run Elementary in Naperville went into lockdown in 2012 following reports of a potentially armed burglar in the area. That same year a gun threat fueled a decision by Barrington District 220 to cancel a high school dance and a girls basketball game.
Before Sandy Hook, which left 20 first-graders and six staff members dead, Zelaya was never asked what her school does to keep kids safe.
Now many parents approach her to question procedures.
"It almost is the reality now," Zelaya said. "We've had fire drills, we've had tornado drills -- now we have secure safety drills. It's unfortunately a sign of our times."