Bullet- Prisoner puzzle

Here I am giving you a puzzle that I once heard from a senior. In an interview, interviewer asked him a puzzle and surprisingly he gave the right answer. At first I was not able to solve this puzzle. See, if you can solve. Don’t see the below answer if you want to solve.

“There is a prison in the middle of a desert. Suppose there are “n” prisoners. There is no fence or any other security measure in the prison. There is a police who is having a gun and it contains only one bullet. He will shoot the last person who would try to escape. How would prisoners escape? Would they able to escape or not? Justify. “

Note: Prisoners have little knowledge of game theory and will think before making any move. They lack unity to run all together or in group. No one wants to sacrifice his life for other. 
P.S. -Answer should be completely logical and 'Prison Break' series fans, please stay away...

Answer: Answer to bullet- Prisoner puzzle

Answer in comment bar if you got better explanation.

~Digvijay Sanjay Patil