Russian definitely. Basically everyone with a German passport fled from that area when the Russian army was about to arrive and those who stayed were forced to leave or being deported... in the best case.
People would rather die on a trail then having to confront the approaching Russian army... they knew that the Russians would basically do the same to them what their own soldiers did to the Russians. (Same reason why German soldiers were also fleeing westward at the end of the war, not to escape being captured - that was inevitable, but to be captured by the Allies/US)
When the Russians arrived at east-prussia, they just took the abandoned homes of more or less innocent people and gave them to Russians while exterminating the German cultural heritage...
But who will listen to your complaints when you just started the most horrific war in the history of mankind?
Anyway, if you ever happen to be in Kaliningrad, the former Königsberg, and take a look around, you can still trace its German roots... in every building that's older than 60 years.