Police said the men broke into the house on Egeria Street, near Donegall Road, on Friday night after 23:00 BST.
One of the men is believed to have had a suspected firearm.
A man, woman and child locked themselves in a bedroom and were not injured.
A window was broken during the burglary but nothing is believed to have been taken.
Police have appealed for information.
Three people including a small child locked themselves in a bedroom after a gang thought to be carrying a gun forced their way into a house in south Belfast.