After a weekend in which mass shootings in El Paso and Dayton killed at least 29 people and injured dozens of others, John Oliver opened Sunday’s episode of Last Week Tonight with pointed comments on the “absolutely appalling” anti-immigrant fuel underlying domestic terrorism. By the time of the show’s airing, it was widely reported that the shooter in El Paso, a 21-year-old white man, had published an anti-immigrant screed online before opening fire at a Walmart on Saturday, killing 20.

The shooting that targeted a prominent, multicultural city along the Mexican border – a place frequently invoked in the president’s comments condemning Hispanic immigrants – demanded, for Oliver, an examination of racism filtering from the top of American government into mass violence. “Clearly, white nationalism and anti-immigrant hysteria did not start with this president,” Oliver said of Donald Trump. But the president “certainly seems to have created an environment where those kind of views can fester and indeed thrive”.

To illustrate the point, Oliver drew up a clip from one of Trump’s recent rallies in northern Florida, in which he whipped up the crowd by claiming that 15,000 migrants were marching to the southern border and asked: “How do you stop these people?” When someone from the crowd shouted back “shoot them!” Trump laughed, shook his head and said: “That’s only in the [Florida] Panhandle you can get away with that stuff.”

The clip is remarkable for several reasons, most prominently, according to Oliver, in that “it is not ‘only in the Panhandle’ where you can get away with that statement. You can now get away with it all over the country and, as he just made painfully clear, any room the actual president is in.”

Oliver described Trump’s comments as “absolutely appalling”, and warned that his callousness “is something we cannot afford to get numb to,” because if Trump’s “only in the panhandle” clip “ever, for even a moment, feels like it’s become normal, we are completely fucked”.

Oliver concluded with a few words of comfort. “I’m sure we’re going to learn more about this story in the weeks and months ahead, and there may be time to talk about it more in depth then.” But in the meantime, “please, after a tough, tough day, please enjoy this nonsense,” he said, before launching into the show’s intro and a segment on prison labor.