This Adverse Event Report, from a study appearing in the New England Journal of Medicine, shows that of 133 children 17 & under on Zoloft there were 2 who reported "Homicidal Ideation". There were no reports of "Homicidal Ideation" in the placebo group.
According to the Physicians Desk Reference, a Frequent adverse reaction is one that occurs in 100 people or less. Homicidal Ideation occurred in 1 in 66 children on Zoloft aged 17 and under.
This Adverse Event Report was the appendix for this study in the New England Journal of Medicine: