World War Two: Sirens sound to commemorate start of war

Events are being held in Poland to mark 80 years since the German invasion which began World War Two.

German President Frank-Walter Steinmeier has asked for Poland's forgiveness for Nazi "tyranny".

The Polish prime minister and US vice-president also delivered speeches.

Poland suffered some of the worst losses of the conflict, with about six million of its citizens killed.

  • Europe