With guns drawn, sheriff's deputies surrounded the Dallas County Records Building early Tuesday looking for a man inside the building that employees said wasn't supposed to be there.
A maintenance crew reported seeing the man inside the building. They added that once they spotted him they backed away and notified authorities of the intruder.
Officers surrounded the building and blocked off Main and Houston streets outside of the building while a search was conducted inside by armed officers.
After nearly two hours, the mysterious man was never found and the scene was cleared.
Police speculate the man may have been trying to break into an office.
The records building reopened in late June after a flood in the basement closed the building for much of that month.