Frankfurt Airport was evacuated today over concerns that at least one person may have entered a security area unchecked.
It led to boarding being halted and a partial evacuation of Terminal 1.
"The cause of the evacuation of the terminal was an error by a security officer".
The family was located, questioned and allowed to continue on its journey, the police added.
Police did not clarify what had triggered the positive explosives test.
On 28 July, some 300 flights were cancelled at Munich airport, Germany's second-biggest after Frankfurt, affecting more than 30,000 passengers, after a similar incident in which a person passed through the security area without being checked.
Parts of Frankfurt airport were evacuated for several hours on Tuesday following a lapse in security in which a French family of four were allowed to leave the secure zone despite testing positive for explosives, federal police said.
Lufthansa, Germany's largest airline, said around 7,000 passengers were affected by flight delays and cancellations and that it had booked 2,000 hotel rooms as a precaution in case people couldn't be put on later aircraft. Frankfurter Allgemeine is reporting that a family from France bypassed security controls when the guards were distracted.
Around 1,500 flights were set to take off or land at Frankfurt airport on Tuesday.
German police defended the evacuation on social media, saying they had to exclude any and every risk.
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