The incident took place on the Belmont Church Road early on Saturday morning.
Judith Cochrane MLA said: “I am shocked and disgusted by this incident and the fact a gun of some description was used is extremely disturbing.
“My thoughts are with the two staff members involved as they recover from what can only have been a very traumatic experience.
“I would urge anyone with information to contact the PSNI as soon as possible to ensure those responsible for this thuggish behaviour can be removed from the streets as soon as possible.”