Rob Kardashian Detained By Police

Sources close to Rob tell TMZ he was out with some friends when he saw a photog taking pictures from across the street. We're told Rob thought it would be funny to start sprinting towards the photog ... but the photog didn't laugh and instead ran away screaming for help.

According to our sources, Rob followed the guy into a smoke shop to try and clear the air (no pun intended) but the police saw the whole thing and decided to get involved.