The wooded lot is near an industrial area of Central Islip
Suffolk County police said the two lived in Hempstead.
Neighbors on Pinewood Avenue and Maple Place watched as investigators searched for clues to the unthinkable crime.
Mike Carney cuts through the area every day and says he was horrified by the news.
"That's the scariest part, the mother and a child, because there's a lot of stupid gang activity that happens around here," he said. "But a mother and a child, that's just not right at all in any situation. It kills me."
Police were still trying to determine who shot and killed the two.
Anyone with information regarding this incident is asked to call the Homicide Squad at 631-852-6392 or call anonymously to Crime Stoppers at 1-800-220-TIPS. All calls will remain confidential.