Three New York men were accused on Tuesday of selling over 100 illegal assault weapons from a shop near Rochester in what the authorities said was the largest gun seizure made by the state attorney general’s office since the SAFE Act was passed by the State Legislature after the 2012 mass shooting at a Connecticut school.

The owner of the gun shop, Kordell Jackson, 40, of West Henrietta, was arrested on charges including three counts of first-degree criminal sale of a firearm, the authorities said. Also arrested were two shop employees: Joshua Perkins, 28, of Irondequoit, and Ken Youngren, 30, who the authorities said was a part-time police officer in the villages of Andover and Belmont. They face charges similar to those brought against Mr. Jackson.

When reached by phone on Tuesday before he was arrested, Mr. Youngren declined to comment. Attempts to reach Mr. Jackson and Mr. Perkins by phone were unsuccessful.

The investigation began in 2014, when agents with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives noticed “irregularities” in the records of the store, Jackson Guns and Ammo in Henrietta, and alerted the State Police, according to a joint news release from the state attorney general and the State Police superintendent.