An airport is being evacuated after an unauthorised person allegedly slipped through security with a child and disappeared.
The airport authorities wrote: "Due to a police action, the German Federal Police is now evacuating Piers A and Z at Frankfurt Airport's T1".
Unverified video footage posted on social media during the police operation appeared to show passengers being evacuated from a terminal.
After the alarm had been raised, the family were located in the terminal, re-checked and allowed to continue on their journey after being cleared.
The terminal resumed operating as normal about two hours after the partial evacuation was imposed.
"Despite a positive explosive test, a four-member French family was released into the security area". The police gave no details on what had triggered the positive explosives test.More news: Chelsea's Willian admits affinity for Jose Mourinho wants Chelsea stay
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Police had cleared some areas in the airport's Terminal 1 and halted boarding in the incident.
Lufthansa, Germany's largest airline, said around 7000 passengers were affected by flight delays and cancellations and that it had booked 2000 hotel rooms as a precaution in case people couldn't be put on later aircraft.
Police at Frankfurt Airport in Germany took the measure over concerns there had been a major security breach.
Some 1,500 flights had been scheduled for taking off and landing at Frankfurt airport on Tuesday, according to airport operator Fraport.
Lufthansa said it was working on a new flight plan and would provide more information later on Tuesday.