Someone asked him a question about him pushing gun control and then he went on a 5 minute long tirade about infrastructure and children's drinking fountains in schools (nothing about guns).
Looks like he screwed up the coordination of reading the wrong pre-written response to the wrong question.
Fucking sad.
In the course of a single fateful evening, America went from having a President who could talk his way out of anything like a used car salesman to a "president" who's just being used.