At 1.23pm today, officers received reports of the crash in a crop field at Aldborough near Boroughbridge.
Katie McCann, of London, who grew up in the village, said the crash took place behind Aldborough Hall.
She was in her mother's house when she heard what sounded like an "out of control plane or helicopter".
"The clouds are quite low here today and it's not great weather.
"Then I heard an enormous explosion."
The 53-year-old looked out the window and "black smoke was everywhere and I just flew out of the house because I thought it was an airplane".
A man with two boys was on the phone trying the direct emergency services, and Ms McCann helped.
"You couldn't see anything," she said. "There was so much smoke.
"[One man] said he had seen it. It was a red and white helicopter.
"He said it had climbed up into the cloud like it was trying to recover itself, and then dropped like a stone."
Pictures supplied by Ms McCann showed a Yorkshire Air Ambulance attending the scene afterward the crash.
"That arrived 10 minutes later," she said. "I couldn't believe how fast they arrived."
It also only took the first fire engine around three minutes to turn up, she added.
Locals had told her a helicopter landed in the nearby Boroughbridge area at around 8.30am this morning.
Officers have cordoned off the area and are currently conducting a search of the scene.
Fire and ambulance crews have also attended the scene.
Police are not yet able to confirm any information about casualties.
Fire crews from Boroughbridge, Knaresborough, Harrogate and Ripon attended, it is understood.