Police and divers spent hours searching the waters of Campbell's Pond in the South Mountain Reservation in Millburn.
Authorities began combing the pond after a local Scoutmaster reported seeing a dog fall in the water and then a man struggling to rescue it.
Essex County Sheriff Armando Fontoura said, "He thought the dog fell through, then as he kept driving, he turned back and didn't see anything. He made a u-turn, came back and again he didn't see anything or anybody so, you know, we hoping that nobody fell through the ice."
Sheriff Fontoura says authorities checked with every police department within 40 miles, but so far no missing person reports had been filed.