A massive search effort is underway in southwest North Carolina where a young boy with autism vanished over the weekend after going to a park with his father.

The search for 6-year-old Maddox Ritch ramped up yesterday as the FBI joined more than two dozen local and state law enforcement agencies to look for the boy, who was last seen at a park in Gastonia, North Carolina, about 20 miles west of Charlotte, authorities said.

Maddox, who is described as nonverbal, was walking near a lake at Rankin Lake Park in Gastonia at around 1:30 p.m. Saturday when his father lost sight of him, authorities said.

In addition to the FBI, at least 24 local and state law enforcement agencies and more than 100 volunteers are helping with the search, according to the Gastonia Police Department.

Gastonia Police Chief Robert Helton said officers were searching the lake, reviewing the park’s surveillance footage and interviewing residents in the area for clues.

The National Center for Missing and Exploited Children, which is also assisting in the search, said Maddox may be in need of medical attention, according to a statement on its website.

Police said Maddox is 4 feet tall with blond hair and blue eyes. He was last seen wearing an orange T-shirt with the words “I am the man” and black shorts.

Anyone with information is asked to call the police department’s special tip line at 704-869-1075.