"I'm so sick of moment[s] of silence," she said. "It's not working."
Instead, the singer called for a moment of action.
"Why don't we do a moment of action? Why don't we do a moment of change? Why don't we change what's happening, because it's horrible," she said.
Clarkson urged everyone to take action in their local communities.
"We're failing our communities. We're failing their families," she said. "I have four children. I cannot imagine getting that phone call or that knock on the door."
The tragedy at Santa Fe High School was the ninth fatal school shooting of 2018, ABC News reports. This year has been deadlier for schools than for active military service.