Twenty years ago today, the nation reacted with horror when two young men in trenchcoats opened fire at Columbine High School in Littleton, Colo., killing 12 students and one teacher. It shocked our collective conscience: How could such a thing happen?

But since then, the horrors have multiplied: Sandy Hook Elementary in Newtown, Conn., with 20 children and six adults killed in 2012; Marjory Stoneman Douglas High School, 17 killed, in 2018; in Las Vegas, 58 killed in 2017; and in Orlando, Fla., 49 killed in a nightclub in 2016.

While they took place far from Hawaii’s shores, we are affected all the same. Our view of what it means to be safe in our communities has changed forever.

Once unimaginable, active shooter awareness and training are now routine for public and private school campuses, including Hawaii’s K-12 schools and the University of Hawaii. A Washington Post analysis found that more than 4.1 million students across the country experienced at least one lockdown in the 2017-18 school year — even though school shootings remain rare. We worry more about threats, credible or not; the worst-case scenarios (see above) weigh on our minds.

But beyond the statistics, those marking the anniversary of Columbine today will weigh the personal, human cost: the lives cut short, but also the forever- changed lives of the survivors, including family members of the victims. They will reflect on their pain and suffering, their shared grief and the slow but necessary process of healing. Columbine reminds us that wherever we live, we have a shared obligation to support each other and do what we can to prevent such tragedies from happening again.