The airport is currently closed, and it is due to two to three drones flying around the airport area, says Henrik Stormer, duty officer at the Copenhagen Police, to the news agency Ritzau.
We have a massive effort in place.
There is no prognosis late on Monday evening for when the airport can reopen.
Among the affected departures is a SAS flight to Stockholm, which was scheduled to land at 22.35 but which, according to Swedavia, will be over four hours delayed.
Incoming flights to Kastrup are being diverted to several airports, according to DR mainly to Billund and Ålborg, but according to Swedavia also to, among other places, Malmö and Landvetter.
The police have a large presence at the airport on Monday evening.