Great ninjas killed children

If you think about it, Minato and Jiraiya did participate in the 3rd ninja wars. And even though anime didn't explicitly show us how those guys kill children, we can see that children in fact did fight in wars. And we know that Minato and Jiraiya become legendary ninjas and probably had insane kill count.

Kakashi, Obito, Rin and other non adult ninjas were shown in Kakashi Gaiden. And even though it's only Konoha child ninjas that were shown to fight in wars, I think heavily implied that other hidden villages also did use children in war.

So, most probably, Minato and Jiraiya killed children