In this communication we consider the problem of optimal control of a multi agents system evolving over a bi dimensional grid. Starting from an initial state, the aim of the problem is to find a global strategy so that the system reaches a desired final state in a minimum time. Each agent is characterized by motion parameters while to each cell is associated a current capacity. Objectives and constraints of this optimal control problem are discussed and a solution strategy based on dynamic programming solution approach is proposed for this discrete optimization problem. The application of interest in this study is relative to emergency evacuation of aircraft. The solution of this problem provides minimum time standards as well as insights for the design of personal guidance assistance in emergency situations.