Immigration officers forced their way into a confectionery plant near Syracuse on Thursday morning and detained more than 70 workers, witnesses said, in what appeared to be one of the biggest workplace raids in New York since President Trump’s deportation crackdown began.

The operation spanned hours and at one point involved as many as 75 law enforcement officers from the Department of Homeland Security, U.S. Customs and Border Protection, and the Cayuga County Sheriff’s Office, according to witnesses.

Brian Schenck, the Cayuga County sheriff, said that his agency had assisted in the raid but he declined to give details, referring questions to the federal Homeland Security Investigations agency. A spokeswoman there did not immediately respond to requests for information.

Ana Mendez-Vasquez, an organizer with the Rural & Migrant Ministry, an advocacy group, who witnessed the raid, said that federal agents arrived at about 9 a.m. at the plant, Nutrition Bar Confectioners in Cato, N.Y. Ms. Mendez-Vasquez said they forced their way inside using crowbars and blocked the building’s exits before handcuffing people inside.

Ms. Mendez-Vasquez said that a Homeland Security agent told observers that the detained workers were taken to the Oswego Border Patrol Station.