MINNEAPOLIS (WCCO) — A powerful new video has people around the nation talking about the early warning signs of gun violence.

The video was created by a nonprofit group that was started after a mass shooting at an elementary school in Connecticut.

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The video shows what appears to be an ordinary day inside a high school.

But a closer look highlights the warning signs of isolation in teenagers and behavior that could lead to violence.

A group called Sandy Hook Promise released the two-and-a-half minute video on Friday, and the response has been overwhelming — it’s been viewed millions of times.

Back in 2012, a 20-year-old man fatally shot 20 children and six staff members at Sandy Hook Elementary School.

The goal of the PSA is to raise awareness of the warning signs that someone may be thinking about carrying out a violent act with a gun.

It’s not something that any of us ever wants to think about, much less talk about — the possibility that a mass shooting could occur.

Psychologists say attackers often demonstrate warning signs ahead of time.

And that is what this video shows.

Dr. Cheryl Bemel is a psychologist with Allina Health who just watched the PSA.

“It was very creative, wasn’t it? And it was alarming, and surprising,” she said.

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The video cleverly reveals how the behavior of a troubled student goes unnoticed by those around him.

It shows a boy and girl exploring romance, but lurking in the background the entire time is another boy exploring his fascination with guns and enduring being bullied.

If you missed it the first time, the scenes replay so you can’t miss the signs.

“We’re surprised and we’re startled, and I think it’s good to be startled. I think we need to be startled. I think that we need to be aware,” Dr. Bemel said.

The founders of Sandy Hook Promise believe that if we don’t “know the signs” of potential gun violence then we risk tragic consequences.

“This is not about mental illness. This is so much more about isolation and loneliness, and not feeling a sense of connection and not feeling a sense of community,” Dr. Bemel said.

Dr. Bemel says isolation can lead to depression and violence.

And she says it’s important that we reach out to young people who appear to be disconnected from other teens or family members. If they seem disengaged, pay attention to them and keep reaching out.

The nonprofit Sandy Hook Promise is focused on prevention and intervention, providing training for school teachers and staff nationwide. To learn more about Sandy Hook Promise, click here.

And here in Minnesota, we know many school districts do offer training to staff that helps them with this kind risk assessment before problems occur.

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Just as important as knowing the signs, is being willing to say something about it if you see them.