Visitors to the National September 11th Memorial Museum reportedly were forced to leave suddenly last week, but museum officials did not make the evacuation public until Thursday.
A Fire Department spokesman tells the New York Times that firefighters answered a call of an "alarm activation" around 1 p.m. last Friday.
It turned out to be a false alarm, and no injuries were reported.
The fire department also says there did not appear to be any problems with the evacuation.
However, the Times says the incident rattled some visitors.
At least one woman tells the paper the evacuation route was a confusing network of hallways and staircases that left her concerned for the safety of herself and other evacuees.