First comes the warning, that disembodied voice over the tannoy: "Your attention please. Air siren in the city. Please move to the shelter on the minus second floor." Then comes the mosquito-like whine of the incoming Russian drones, massing in their hundreds just above the clouds.
It's followed immediately by the rattle of anti-aircraft fire, the distant thud of explosions, then finally the ominous klaxon call of ambulance and fire sirens.
This is the grim reality of night time in Kyiv and other cities across Ukraine.
These are attack drones that explode on impact.
Drones are now an integral part of modern warfare, but they are not confined to the battlefield.
Across western Europe, far from Ukraine, unarmed drones have also been found buzzing around airports, military bases and power plants, all part of a suspected programme of "hybrid warfare" being waged by Russia, with some speculating they're arriving to test the resilience of certain Nato countries that are helping Ukraine.