Children do not have to go to Hell. In fact, nobody has to go to Hell.
Years afterwards, as I was asking God why kids are in Hell, I felt that He said,"Why should I only send the older people? Why should I send people of a certain age to Hell for sin and not send the kids especially when they know they sin, and choose to sin?" It caused me to think about the kids who shot and killed other kids in the schools... they knew what they were doing.
Years ago, I felt in my heart that the age of thirteen was a child's age of accountability, but the hearts of children have increased in hardness and evil in these wicked times. I have to recognize that holiness (and a child's innocence), not a number, is God's standard of righteousness.