The caller was a part-time employee with the parks and recreation department.
"We got a missing kid," the man told dispatchers. He was referring to 6-year-old Maddox Ritch, who police say has autism and is nonverbal.
He disappeared around 1:30 p.m. Saturday after going to Rankin Lake Park with his father and another adult.
A search dog from the @MissingKids inside drainage pipes. We are searching everywhere possible to #FindMaddox. Call the @GPDNC tip line! We desperately need to hear from those in the park on Saturday. 704-869-1075. pic.twitter.com/A66XksUEhC— FBI Charlotte (@FBICharlotte) September 26, 2018
The father told police that the boy ran off and, when they started running after him, they lost sight of him.
The 911 caller said the boy had disappeared about an hour before he called. "We searched everywhere," he said.
He also told dispatchers that the parents were at the park looking for the boy.
In an exclusive interview with ABC News, Maddox's dad, Ian, said he can't stand the thought of where his son might be right now.
"It's been hard to sleep," he said. "I feel guilty because I can go into a house, lay down in a bed, and my little boy might be out there in the woods."
The FBI is offering a $10,000 reward for information that leads to the location of Maddox.
The public is invited to a candlelight vigil Wednesday at 7:30 p.m. at the Rotary Pavilion in downtown Gastonia.