Montgomery County animal services officers seized 66 dogs from a home in the Rockville area and relocated them to the county’s animal shelter in an operation that began on New Year’s Day and may be one of the largest such efforts in recent years, authorities said Sunday.

The dogs had “a variety of medical issues and conditions, some more serious that others,” said Thomas Koenig, director of the animal services division of the Montgomery County Police Department. Some required immediate veterinary care, he said.

Authorities say the case started after two animal services officers knocked on the door of a home in the 13000 block of Glen Mill Road on New Year’s Eve to investigate a dog bite case.

The homeowner was uncooperative and did not allow the officers to inspect the premises to locate the dog in question, officials said. But the officers took note of the property’s condition, suspected a large number of animals were being housed and returned a day later with police to execute a search warrant, officials said.

“Based on what we saw, we felt it was in the best interest of the dogs to remove them from the home,” Koenig said.

The removal, processing and examination of the 66 dogs - who varied in breed, age and size - lasted through the night, taking nearly 16 hours. The animals are now in county custody at the shelter, the Montgomery County Animal Services and Adoption Center, a 50,000-square-foot facility in Derwood. A number of the dogs likely will require additional treatment or further examination.

Officials said the investigation is continuing and will consider issues of cruelty and abuse, and whether there was any history of complaints against the owner. Charges have not been filed, and the homeowner’s name was not released. Koenig said charges could come as soon as later this week.

“I don’t recall a larger case than this that my officers have worked,” said Koenig, who has led animal services in Montgomery since last April and previously held a similar post for a decade in Loudoun County.

In Loudoun County, 54 dogs and a cat were seized from a Purcellville property in 2011, he said.

Jill Asman, a neighbor in the Rockville-area community where the dogs were removed, said houses in the area are set apart, situated on lots of an acre or more, and some properties are screened by trees. Still, she was stunned to hear about the number of animals found.

“Sixty-six is beyond anything I could imagine,” she said. “I had no idea.” About five years ago, she recalled a day when there was racket from dogs barking, but more recently she had not heard the animals.

“This kind of thing, it’s really sad,” she said, thinking of both the animals and her neighbor’s housing of so many pets.

Another neighbor, who asked not to be identified, said the homeowner with the dogs seemed like “a friendly, nice lady” but that she did not know her well.

“We did hear sort of constant little yapping over there,” she said, “but nothing of the magnitude of 66 dogs.” At times, there also seemed to be a whining sound, she said, but “there wasn’t anything that would jump out at anybody.. . .nothing to suggest so many animals.”

Montgomery County officials did not release information Sunday about whether the homeowner who had the dogs was involved in an animal rescue organization.

Rescue organizations provide a valuable resource to communities, Koenig said. But he said sometimes individuals “act on their own passions and exceed their ability to care for all the animals they take in.”