Most children killed by guns handled them in their homes, and accidents at expos and shooting ranges are much less common, according to Gates.
But even though Massachusetts law, and those of many other states, allow children to shoot weapons in a controlled environment, the Children's Defense Fund's policy is that those laws aren't strong enough.
"It is so dangerous, as well seen by this incident, to handle any type of loaded gun, never mind a loaded Uzi," Gates said.
William Hockla has lived across the street from Biziljs for years and said Christopher was very bright and active. He heard about the shooting on the radio this morning.
"I was hoping it wasn't true," he said.
He described Charles Bizilj and his wife Suzanne as involved parents who took their two boys camping, fishing and skiing.
"They were very polite, well-groomed," he said. "Terrific boys."