A door assembly including a frame with an opening having a first portion and a second portion. The door assembly includes a first panel movable between a closed position in which the first panel generally covers the first portion of the opening and an open position in which the first panel generally does not cover the first portion. The door assembly has a second panel movable between a closed position in which the second panel generally covers the second portion of the opening and an open position in which the second panel generally does not cover the second portion. The second panel is configured to block the first panel from moving to its open position when the second panel is in its closed position. The door assembly further includes a controller operatively coupled to the second panel to selectively block or enable movement of the second panel from its closed position to its open position or from its open position to its closed position.