ROCHA
I too have 3 boys, ages 9 6 and 5!! And even though they haven't pulled that stunt yet there have been others.

Don't you just love 'em.
I think making them confess to their actions, no matter what their ages is the first place to start. See what ideas your neighbor has to make up for what they did. Just the embarrassment of confessing alone will teach them a very big lesson. Make them do what ever your neighbor has in mind, and they will learn even more.
Good Luck! I am feelin the pain right with ya.