After an intense 48-hour search, a missing 9-year-old girl who disappeared over the weekend while on a camping trip with her family in upstate New York was found safe Monday evening, and a suspect was in custody, according to New York State Police.

The girl, Charlotte Sena, went missing during an early evening bike ride on Saturday in Moreau Lake State Park, about 45 miles north of Albany. Soon after her disappearance, Charlotte’s bike was found, leading authorities to believe that she had been abducted, a scenario that the state’s governor, Kathy Hochul, called “every parent’s nightmare.”

Indeed, Charlotte’s disappearance has riveted and terrified parents nationwide, even as experts cautioned that such kidnappings are rare. The circumstances of Charlotte’s abduction had echoes of the 1996 kidnapping and murder of Amber Hagerman, another nine-year-old girl who was snatched by a man while riding her bike in the Dallas area.

Amber’s death was the inspiration for Amber Alerts, which broadcast information on a variety of mediums about children that are deemed to be in imminent danger. In Charlotte’s case, such an alert was issued Sunday morning, after New York authorities had already been scouring the park for hours, using bloodhounds and aerial units, as well as park rangers and boats to search the park’s small lake.

On Monday night, Gov. Hochul praised those efforts, as well as the state police ”and all who worked so tirelessly to find Charlotte.” Some 400 law enforcement officers and other personnel had joined the search, including park rangers and private companies.

“We are overjoyed at the news that Charlotte Sena has been located safely,” Ms. Hochul said, adding, “Our hearts are with her family as they welcome her home.”

Charlotte’s family had pleaded with the public to share her photo widely in hopes of finding their niece, even as reporters and rescuers descended on the park, a popular area marked by dense forest and undergrowth.

“Any information would help,” said Jené Luciani-Sena, Charlotte’s aunt, in a video posted to TikTok on Sunday night.

Authorities also seemed eager for assistance, putting out a lengthy release just hours before Charlotte was found, asking for tips. “No detail is too small when searching for a missing child,” it read.

The circumstances of Charlotte’s abduction were harrowing: she was last seen riding bikes with friends on a small loop road inside the park — ringed by campsites — at a little after 6 p.m. on Saturday. Charlotte decided to go around the loop one more time by herself, and did not return.

Her parents went to look for Charlotte, a search soon joined by other campers and a crush of law enforcement personnel. They combed the woods for signs of her but came up short. On Monday, that search continued at the park — which was closed — with bloodhounds darting into the underbrush, trying to catch a scent.

Others had come to the park offer whatever help they could, including Patrick Kane, who said he’d hoped to help search, but wasn’t trained and thus turned away. He said he’d texted with Charlotte’s father, David, who he is friendly with, and said the family had remained “optimistic” that his daughter would be returned safe.

“These are wonderful, wonderful people,” Mr. Kane said. “We never want this to happen to anybody. But you are just shocked when it happens to someone like this.”