We must mourn. We must reflect. We must act.

Our hearts ache and our minds reel. A deadly antisemitic attack has been perpetrated on American soil. Innocent lives have been lost at the Tree of Life Synagogue in Pittsburgh where a celebration of life was taking place.

While mass violence is all too well known in this country, this particular attack was directed at Jews, a group that is no stranger to the dire consequences of racial animus. The perpetrator is apparently a white supremacist who yelled “All Jews must die" before opening fire.

Now is a time to mourn those who have been wrenched away from their families at a time that should have been filled with joy. It’s a time to grieve for their families and friends who will forever struggle to understand what happened on Saturday.

But it also a time to look deep into ourselves. History has demonstrated time and again that when white supremacists say they will harm Jewish people, violence follows. When they say they will kill, kill they do.

Through our tears, we must find the strength to act. Saturday’s atrocity must be a call to people everywhere to wake up to the underlying lethal nature of antisemitism. We must work with legislators, policymakers and educators to bring about the changes we need to work so these acts of terror are not repeated.

There are many resources available to learn how to counter antisemitism and hatred in all its forms. Among them is USC Shoah Foundation’s free IWitness portal. IWitness offers a wide variety of learning activities that tackle some of today’s toughest subjects for students in middle school, high school and universities.

We’ve seen time after time that the voices of the 55,000 survivors of genocide who gave us their testimony can act as a signpost to lead the way to teach the empathy and respect we so sorely need. Those who have faced these tragedies and shared their stories can help, and our aim is to share their comfort and guidance.

We are going to redouble our efforts to counter antisemitism through our programs across the United States. We are going to educate from our archive, empowering the voices that know personally just how lethal antisemitism can be. And we are going to widen our community of educators and students prepared to counter this deadly force with their voices and their actions.

Hate is a pernicious virus that spreads through apathy and neglect. But by working together, we can be stronger than hate.