Police are searching for a 5-year-old boy who fell into the Harlem River Saturday afternoon.

The child, who was with his parents, was last seen climbing a tree at around 2:50 p.m. near the water at Harlem River Field 7, sources told The Post.

“Everybody was just playing around and I guess they went to the side of the water and something must of happened,” said Luis Ramos, who was nearby coaching kids playing soccer when the accident happened.

“The parents jumped in, that’s why they’re wet. They jumped in to look for him. A couple of other parents jumped in too. The thing is it’s so dark you can’t see anything in the water,” Ramos continued.  “I heard the parents going: ‘Over there! Over there!’

Ramos continued: “I saw a little arm out of the water, that was it. The last thing I saw was an arm sticking out.”

Harbor and Emergency Service Unit aviation are among those involved in the rescue operation.