Students are evacuated by police from Marjory Stoneman Douglas High in Parkland, Fla., on Feb. 14 after a gunman opened fire on campus. (Mike Stocker/South Florida Sun Sentinel/AP)

A 2016 report by the U.S. General Accountability Office — undertaken in part as a result of the 2012 shooting deaths of 26 students and teachers at Sandy Hook Elementary in Newtown, Conn. — found that 40 states reported requiring schools to conduct emergency exercises to prepare for such a disaster.

While there are conflicting views about whether active shooting drills calm students who feel prepared for such a disaster — or create anxiety in them — active-shooter drills have become increasingly common for children of all ages, even as young as 2.

Law enforcement, school districts and even the Department of Homeland Security offer free active-shooter training online, and private trainers are offering their services free in the wake of this week’s killings of 17 people at a South Florida high school.

Here are some reactions from parents and others to the reality that in the United States, active-shooter training for kids is now routine because school shootings have become sickeningly routine.