Two years ago, my son was killed by a mass shooter. I’ve never spoken about it publicly until now.

The last two years have been the hardest of my life.

My son Chris was just 20 years old when he and five others were murdered in a shooting rampage near the University of California, Santa Barbara. One moment, he was just a sophomore English major, grabbing a snack with friends at a deli near campus — in the next, his life was stolen from him without warning.

As a parent, you worry about lots of things, but something like this was simply unfathomable to me. Even as I rushed to the scene after getting the call that Chris had been shot, I kept thinking he’d be OK — that he couldn’t possibly be gone. Today it’s still almost impossible for me to process.

The media often refer to tragedies like my son’s death as “random” acts. But gun violence has become all too commonplace. Every year, 33,000 Americans — each one of them someone’s son or daughter — are killed by guns. That’s more than three times as many gun deaths as in any other developed country. And there is nothing random about our nation’s inaction.

I remember the horror so many of us felt after Sandy Hook. And I remember my disbelief in the aftermath, when nothing happened — Congress couldn’t come together to pass the kinds of reforms that might have saved lives. But I never could have imagined that one of those lives might belong to my only child.

Politicians are quick to offer condolences in the wake of every shooting, but few have the courage to act. We have to demand more. That’s why I’m sharing my story publicly for the first time — and it’s why I’m supporting Hillary Clinton.

Hillary has spent her career working to end gun violence. She has brought the issue front and center as a presidential candidate, and I truly believe she’ll make it her mission to address it as president. That means standing up to the all-powerful gun lobby, enacting comprehensive background checks, and keeping guns out of the hands of domestic abusers and other dangerous individuals.

And we can’t wait any longer.

A few weeks ago, one of Chris’s former professors gave his father and me a stack of essays Chris had written as a student. I read them again and again, and I can’t help but think about what a wonderful, bright young man he was and what a promising future he had ahead of him — a future that never should have been lost.

I will do anything I can to keep other families from going through the unimaginable pain we’ve been through. That’s why I’m speaking out now, and it’s why I’m putting my faith in Hillary.