This storm did some things that were very, very unusual, and that is why so many chasers got caught off guard. Most tornadoes move in a SW -> NE direction. At the time, the chasers were just NE of the storm, and this one appeared to be moving due east. As it approached, it intensified dramatically and made a hard right turn to the south. The chasers were along a N/S road, heading south, and were in good shape to do what they do (deploy probes and instruments in front of it, move south, let the storm pass by, then go back and retrieve their equipment). As they headed south, the storm quickly intensified and grew dramatically (NWS has recorded this tornado as being 2.6 MILES WIDE!) They saw the intensification, and realized they needed to get moving. Unfortunately, the tornado also turned south and overran them as they thought they were getting out of the way. These guys were following all the normal "rules of tornado chasing". Get south, and you will be fine. This storm went south, and that is what resulted in this tragedy.