On Sunday's episode of "Last Week Tonight," host John Oliver slammed some of the Republican presidential candidates for their reaction to last week's mass shooting at an Oregon community college that killed nine people. Donald Trump, Ben Carson, and Mike Huckabee all cited mental health issues as the reason for the mass shooting at Umpqua Community College.

"There's nothing like a mass shooting to suddenly spark political interest in mental health. The aftermath of a mass shooting might actually be the worst time to talk about mental health," Oliver said. "The vast majority of mentally ill people are nonviolent and the vast majority of gun violence is committed by non-mentally ill people. In fact, mentally ill people are far likelier to be the victims of violence rather than the perpetrators."

Oliver argued that the entire mental healthcare system needed a massive overhaul and since the issue was dominating the news cycle, now would be a good time to come up with a good strategy.

Oliver ended the segment when he played clips of Trump, Carson and Huckabee as they claimed the Oregon mass shooting was due to mental health issues.

 "If we're going to constantly use mentally ill people to dodge conversations about gun control, the least we owe them is a f---ing plan," Oliver ended.

Check out Oliver's argument below!