A federal police spokesperson said flights had been suspended at Hamburg airport at around 6 a.m. after nine unauthorized people entered an area near the airfield, with eight of them gluing themselves to the ground.
Though flights resumed roughly four hours later, the airport said 17 arrivals and 19 departures had been cancelled on Thursday - the start of school holidays in the region - and further delays and cancellations could not be ruled out. Air traffic at Dusseldorf airport in western Germany had partially resumed after disruption and delays.
"Seven people gained access to the inner area of the airport and stuck themselves to the runway," a regional police spokesperson said. "Three of them could be unstuck quickly, four others are about to be removed."