The soldiers weren't immediately recognized, WROC-TV of Rochester reported.
The Monroe County Sheriff's Office said the crash happened in a farmer's field in the town of Mendon, roughly 15 miles south of Rochester, approximately 6:30 p.m.
Emergency crews"moved to life threatening manner," upon arriving at the scene,'' Monroe County Sheriff Todd Baxter said during a press conference.
"That is a significant heavy weight on all people," Baxter said, as stated by the channel . "We are awaiting the National Guard for affirmation of that had been on board and identification of our great soldiers"
New York Gov. Andrew Cuomo published an announcement on the wreck. He stated flags at all state buildings could be reduced to half-staff on Thursday.
"I'm devastated by the news of a New York Army National Guard helicopter accident in the Town of Mendon that murdered three of New York's bravest through a practice mission," Cuomo said.
"National Guard members are our citizen soldiers who willingly serve and protect both here and overseas, and I extend prayers and condolences from all New Yorkers into the family, loved ones, and fellow soldiers of those honorable personalities who we'll not forget," he continued.
Roads close to the wreck could stay closed"throughout the overnight," with just neighboring residents allowed accessibility, police said.
The wreck stayed under evaluation , officials said.
"We request that you please keep the families and loved ones of those deceased on mind since the research into this horrible crash proceeds," the sheriff's office tweeted Thursday. "Thanks to all our 1st responder spouses to people who brought food/drink to the spectacle."