Searchers were continuing the search Tuesday night for a 3-year-old girl believed to have fallen into the waters of Lake Powell.

National Park Service rangers have been using a robotic submarine to try to find Kamberlie Binks of South Jordan, who vanished from the dock at Bullfrog Marina on Monday afternoon. Her parents were working on their houseboat, Kane County Sheriff Lamont Smith said.

"Their two kids — a 3-year-old little girl and a 4-year-old boy — were just there on the dock right by them," Smith said Tuesday. "They just turned their heads for a few minutes and the little girl was not there."

Deputies said the parents searched the boats nearby but found no sign of the toddler. Now, searchers believe the girl may have fallen into the water. Depths in the area range from 130 to 180 feet.

"This is right underneath the houseboats, so it's hard to maneuver," Smith said. "The park service had their dive team there and they just couldn't get down deep enough and stay down long enough, so we're trying the robot."

Smith said the family of the little girl is trying to keep hope alive.

"We're just hoping she'll walk out from a boat," the sheriff said. "They've done a thorough search of the area and haven't come up with her yet. That's why they're concentrating on the water."