The male was observed running through the building carrying what appeared to be either a rifle or shotgun protruding from a case.
The male was wearing all black, with a black pullover hat and a red bandana on his face with white gloves.
He was described as being approx 5'10, darker skinned (possibly Hispanic or light skinned black male), with a stocky build.
The male was seen running down a hallway, past the front desk and exited on the south side of the building.
Police say the male did not say anything and his intentions are unknown at this time.
It is believed he entered an unlocked door on the east side of the building.
A perimeter was established by police and the grounds were searched.
The suspect remains on the loose.