From NPR:

Based on surveys Barnes collected, the top five worries of parents are, in order:

Kidnapping School snipers Terrorists Dangerous strangers Drugs

But how do children really get hurt or killed?

Car accidents Homicide (usually committed by a person who knows the child, not a stranger) Abuse Suicide Drowning

Why such a big discrepancy between worries and reality? Barnes says parents fixate on rare events because they internalize horrific stories they hear on the news or from a friend without stopping to think about the odds the same thing could happen to their children.