Mendon, New York - Three soldiers were killed in upstate New York on Wednesday when a National Guard helicopter crashed near Rochester, according to local media reports and law enforcement.

Local Rochester television station WKBW reported that the helicopter crashed in the town of Mendon, 20 minutes south of Rochester, around 6:30 PM on Wednesday night.

WKBW cited the Monroe County sheriff's office as saying the helicopter went down in a field in the town of Mendon. The crew were reportedly on a training mission.

Earlier the Monroe County sheriff's office tweeted that "a military helicopter with what is believed to be 3 souls on board went down in a field."

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"Tonight we are devastated by the crash of a New York Army National Guard helicopter in the town of Mendon that killed three of New York's bravest during a training mission," New York Governor Andrew Cuomo tweeted.

What caused the copter to crash is unclear. An investigation into the cause has been launched, according to the WKBW report.

Cuomo ordered that flags on all state buildings be lowered to half-staff on Thursday.