HALIFAX -- Police in Halifax are telling people to watch what they post on social media after a photo of a man holding a realistic-looking paintball gun prompted a partial evacuation of a university dormitory.

Investigators say security staff at Saint Mary's University were shown a photo Friday evening of a man holding what appeared to be an assault rifle inside of a university residence.

Police say they were then called to the building and evacuated the floor where the student suspected of being in the photo lived.

The student was not there, but was found at another location and was taken into custody.

However, police soon learned the item in the photo was a paintball gun, not an assault rifle.

Halifax police say people should not post photos of themselves on social media with guns that appear to be real.

"Police have to treat these investigations as if they were firearms which could potentially lead to dangerous situations," Halifax Regional Police said a news release.

"It also ties up police resources and could result in various charges for the person posting the pictures."

Halifax police said no charges were laid in this case.