To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Share Embed Share URL Video File Node URL Embed Code <iframe title="MRC TV video player" width="640" height="360" src="https://www.mrctv.org/embed/140009" allowfullscreen></iframe> GOP presidential candidate and retired neurosurgeon Dr. Ben Carson told Fox News' Martha MacCallum on Wednesday that sutdents need to be trained on what to do in the event of a school shooting.