The partial evacuation of Frankfurt airport is over and "operations are in progress again", German police said on Twitter.
"Terminal evacuation at # Frankfurt #Airport is completed. The affected areas are open and operations are progressing again," the police said.
The T1 Terminal of the airport had been evacuated due to a police operation, the police said on Twitter. All boarding procedures were temporarily halted during the police intervention.
Speaking to the German press agency (DPA), police spokesperson Reza Ahmari explained that the intervention was a response to the illicit entry of "at least one person" into the secure area of the airport.
The evacuation was prompted by a security assistant mistakenly allowing the French family of four into the secure area even though they were supposed to be subject to a secondary screening.
The family was located, questioned and allowed to continue on its journey, DPA said in its report.
According to the airport operator Fraport, the interruption of boarding led to the cancellation of at least 49 flights.
Several planes are currently still stranded on the tarmac as they await new instructions. However, the B and C sections of terminal one remained operational throughout the police operations.
A Fraport spokesperson announced that some flights had been rerouted to nearby hubs such as Munich, Zurich and Vienna.
Lufthansa, the largest airline at the airport, also reserved a large number of hotel rooms in the Rhein-Main region as a precautionary measure in response to the intermittent disruption of traffic.
A similar aviation security incident at Munich airport in July led to the cancellation of at least 200 flights and widespread delays which affected around 5,000 passengers.
At the time, police only re-opened the affected secure area of the airport two hours after its evacuation.