How is suspense created during the briefcase exchange scene in the film 'Collateral'

During the start of the film Collateral, Felix is walking through an airport whilst carrying a briefcase, he then bumps into a stranger also carrying a similar looking briefcase, when the two collide both briefcases are dropped and each one falls into the hands of the wrong person.
This moment feels very suspenseful since it begins in slow motion which lets the audience know that the film is building up to something big, in addition, the sound of their footsteps getting nearer also increases the level of suspense because the audience almost feels as though something is coming towards them.

To add to this, once each briefcase is dropped, the distance between felix and the stranger becomes much closer, therefore, we feel more uncomfortable, thus making the feeling of suspense even more evident.