The minister was attending the Ukraine Peace Summit in Switzerland.
One of the arrested men was also charged with preparing a terrorist act.
A 6-year-old child was one of the people killed.
Local media said the attacks were the largest air assault on the Lviv region since the Russian invasion in February 2022
It's the second time New Zealand has turned down President Volodymyr Zelensky's invitation.
"The destruction of the Kakhovka dam today puts thousands of civilians at risk."
Ukrainian and Russian forces are blaming each other for the breach.
His funeral will be held in Auckland next week.
The kiwi soldier will be remembered as a man amongst men with a "wicked sense of humour".
