It could be anger initially, and with more understanding of Dhamma, one realizes that those people commit such actions out of ignorance. One feels bad about them too, since they are destined to suffer so much due to such actions.
So, yes. There could be some anger involved too, but overall one will have more “good thoughts”, especially after taking action. Humans have an innate understanding of what is right and what is wrong. So, many times, people do the right thing instinctively.