After a bank was robbed, the bank tellers and the customers got up off the floor where they had been held at gunpoint. because it was such a frightening experience, they are likely to have experienced a rapidly occurring chain of internal physical reactions called:

the fight-or-flight response.

Explanation:

The fight-or-flight response which is also called acute stress response is a physiological reaction that occurs to us if we are facing a scary situation or something that disturbs us mentally.

When we are faced with a terrifying situation our release hormones which can help our body choose to whether run away from a terrifying situation or face of and fight it.