Late night hosts weigh how to open comedy programs in wake of Boston marathon attacks [VIDEO]

With three dead and more than 100 injured in bomb attacks at the Boston marathon Monday afternoon, late-night TV hosts once again struggled to open comedy programs in the wake of disaster. "We have a great show for you tonight -- but first, I have to mention what an upsetting and sad day it's been," Conan O'Brien said, turning on a dime, at the top of his TBS show.