The 2013 European Biathlon Championships opened up with the junior women's and men's individuals on Wednesday with Zagoruiko and Semenov claiming the first senior gold medals.
Zagoruiko skied fast and shot clean to take a dominant victory in the 15km clocking 48:04.9minutes with Ane Skrove Nossum taking silver and Monika Hojnisz bronze.
Hojnisz won bronze in the mass start at the World Championships in Nove Mesto on Sunday while Semenov incurred one penalty in the 20km but still won by almost 15 seconds.
The Ukrainian recorded a winning time of 52:50.2, 14.3 seconds ahead of Tobias Arwidson, who shot clean while the home nation had something to shout about as Krasimir Anev took bronze.
Anev could have easily have been toasting silver however he broke both his poles on the last loop, one just as he came out of the range and the other during the lap.
Heavy snowfall set in for the men's race but Semenov admitted it affected him little as he admitted to claiming an unexpected victory in Hungary.
"During the race I did not get any information from the coaches except 'everything is OK, go on, go on'. I did not expect to win," said Semenov.
"At the last shooting I was still very nervous and my legs were shaking. On the last loop the coaches told me I was six seconds behind Tobias.
"The French athlete ahead of me [Florent Claude] had a very good last loop and I could go behind him, this was very good for me."