Massachusetts authorities continue their search Monday for a 4-year-old autistic boy who went missing in South Boston over the weekend.

Massachusetts State Police reported the disappearance of Mohamed Fofana, of South Boston, on Twitter. They said the boy disappeared nearby castle islandthe northern end of a stretch of Boston beaches overlooking Boston Harbor.

«Potential reasons have not been ruled out» for the boy’s disappearance at this time, state police said.

Marine units and dive teams from various law enforcement and public safety agencies were searching the section of ocean known as Western Way, which connects Dorchester Bay to the south and Boston Main Channel to the north, Monday, state police said.

Side scan sonar was being deployed from three ships, providing a sonar image of the ocean floor. Divers will investigate any anomalies detected by side scan sonar, state police said.

They are also conducting what amounts to an underwater search along the entire length of the Castle Island boardwalk up to 150 yards out to sea, state police said.

The state police Air Wing and the US Coast Guard conducted aerial searches along the shoreline, which was also being searched by drone with the Boston Fire Department, state police said.

Detectives reviewed the camera footage to determine Mohamed’s possible route of movement from the playground, police said.

The search Sunday, police said, included his marine unit, a diving team and an air wing. Boston police, fire and emergency medical services along with the Massachusetts Environmental Police also helped, state police said.

Mohamed Fofana.@MassStatePolice via Twitter

The boy was last seen wearing a gray hoodie, blue jeans and blue shoes. They urged anyone with information to immediately call 911.

He was playing at a park on the coast Sunday around 7 p.m., state police said. An adult relative was with the child when the relative lost sight of the child.

That relative called 911 and reported the boy missing around 7:30 p.m., state police said.

Troopers with the Suffolk County State Police Detective Unit also responded, state police said.

nbc boston reported that the boy’s mother said she was with her grandfather and sister when she disappeared. She also said that he has autism and doesn’t speak. The boy has a tendency to wander, the news outlet reported.

“Yesterday they came with grandpa to the playground,” the boy’s mother, Mantenjay, told NBC Boston. “She called me, ‘I see your daughter but I’m not seeing Mohamed.’ That’s why I came here yesterday. I don’t see it… I need to find Mohamed because Mohamed doesn’t do anything himself, nothing”.