The airport was closed for several hours before reopening early Tuesday, causing numerous delays and travel disruptions to 20,000 passengers, airport officials said. The unidentified drones were observed near the airport, causing around 15 flights to be diverted, police and airport officials told news agency AFP. "The airspace over Copenhagen airport has been closed since 8:30pm due to two to three unidentified drones. No aircraft can take off or land," airport spokeswoman Lise Agerley Kurstein said late on Monday. "We had two different drone sightings," Oslo airport spokeswoman Monica Fasting told AFP.