It wasn't difficult to get the first zombie to follow them. He was so angry at being hindered by something he couldn't see that once he made it out of the devil's trap he melted all the asphalt in a ten foot distance from either side in a soundless explosion of raw power. Several zombies were caught in the blast radius and kept trying to move even after their bones were welded to the ground.
The first zombie stumbled after the two humans. His pursuit was relatively slow, but it soon picked up as the zombie fell into a loping rhythm. They almost made it until several more zombies surged out of a building as the glass window exploded. Just then, the first zombie caught up just close enough to curl a fist of telekinetic power around the darker man's neck and yank, dragging Angel backward as the rest of the dead flooded around Dean.