Airport operator Fraport said in a Twitter message today that the airport was returning to normal operations after a disruption that lasted about two hours.
All passengers were evacuated as a precaution and had to go through security controls again.
Fraport said there were some delays caused by the incident and advised passengers to check with their airlines on the status of their flights.
The dpa news agency reports police found no threats to security during their search of the terminal and have taken a woman into custody.