Crews had pulled her grandfather's body from the Kankakee River in eastern Illinois just hours earlier.
"People were like, 'Who's that little girl? That can't be her, can it?"' Kankakee Sheriff's Chief Deputy Ken McCabe said. "I went up to her (and) asked, 'How you doing? What's your name?"'
When authorities told Hannah Klamecki's family — already grieving the loss of her grandfather — that she was alive, the home erupted in screaming.
"It was very emotional," Momence Fire Chief Dave Horn said.
Searchers gave Hannah — a little dirty but unhurt — a banana and water, but she asked for a chocolate cookie. She was taken to a hospital as a precaution, McCabe said.
"It's a tragedy that the gentleman drowned. It's a bittersweet moment that she was OK," he said.
Hannah and her grandfather, David Klamecki, 62, were last seen Wednesday evening on the river near Momence, about 45 miles south of Chicago.
Authorities believe the river current swept the girl away from a small island where she and her grandfather had stopped to swim and to the shore of the mainland where she eventually was found.
She told searchers she was wearing floats on her arms and pulled herself from the water with a branch.
"That's a tough little girl, I tell you," McCabe said.
Hannah, who was barefoot and had scratches from walking through the brush, told her mother that she had taken off her bathing suit because it was muddy, authorities said.
On Friday morning, searchers found her grandfather's body near the island, which is close to a part of the river locals call "Whirlpool Bend" because of strong currents from the union of the river and two tributaries.
The surrounding area is wilderness with no homes, and populated "only by coyotes and deer," Horn said.
The girl's footprints were still visible on the island beach. Searchers believed she had drowned and were scouring the area with a team of divers, sonar equipment and a helicopter.
When the girl appeared just before 10:30 a.m., in an area about three-quarters of a mile from where she's believed to have reached the shore, "she looked in pretty good shape," McCabe said.
"We were most certainly surprised to find her alive and well," he said.
The girl was reunited with her parents, who were waiting with family and friends at the grandparents' home.
Brian Little, a close family friend of Hannah's parents, said the girl's grandparents live near the river but Hannah didn't know the way back. She was visiting them alone this week. She has two younger sisters.
He said he was standing outside the Klamecki home in Momence when the call came about Hannah discovery.
"There was a lot of celebrating, screaming and hugging," he said.
Hannah's father, Mike Klamecki, is senior pastor at New Hope Community Church in Villa Park, Little said. Parishioners there have been "praying for his whole family."
"Obviously, we're giving all the glory to God on this one," Little said.