The first days of this year's Sturgis Motorcycle Rally in South Dakota were among the busiest that local authorities say they have ever seen even as experts warn the gathering could lead to a surge in COVID-19 cases.

“There are more people here than in the 31 years I’ve been doing this,” Meade County Sheriff Ron Merwin told the Rapid City Journal in an article published on Saturday.

According to Merwin, the sheriff's office has received 104 calls for service since Friday, when the rally officially kicked off, mostly about traffic stops and accidents — nearly double the traffic calls received last year.

“I don’t know what it is this year, but it seems people are in a hurry to get here and are causing all kinds of traffic issues,” the sheriff said. “We are asking the public to please follow our traffic laws and be safe out there.”

Sturgis Police Chief Geody VanDewater told the Journal that 207 open container violations have been issued so far, including two arrests.

Experts have been raising coronavirus-related concerns about the rally since before it started, particularly with the more contagious delta variant spreading across the U.S. Last year's rally was believed to be a superspreader event linked to thousands of cases.

Top White House medical adviser Anthony Fauci on Sunday remarked that he was "very concerned" about the potential of another surge in cases in the South Dakota region.

"I mean, to me it's understandable that people want to do the kinds of things they want to do. They want their freedom to do that," Fauci said on NBC's "Meet the Press." "But there comes a time when you're dealing with a public health crisis that could involve you, your family and everyone else that something supersedes that need to do exactly what you want to do."

An analysis released last year determined that the Sturgis rally was linked to more than 266,000 COVID-19 cases. South Dakota Gov. Kristi Noem (R) baulked at the analysis, claiming it was "fiction." Noem is expected to attend the motorcycle rally this year.

According to the South Dakota Department of Health, around 60 percent of the state's total population has received at least one dose of a COVID-19 vaccine.