Several Unidentified Flying Objects (UFOs) which changed colour were spotted in the Andover, Massachusetts skies, late in the evening of 19 December.

The sighting made news after a video of the mysterious object suspected to be an UFO was posted on YouTube by a user named 'RealUFOs2009'.

Triangle UFO over Andover Massachusetts 19th December 2013
Triangle UFO over Andover Massachusetts 19th December 2013 (Screen grab)

"Left work at approximately 5:54 pm, came out of building which faces towards the river (north). Sky was clear, could see stars, no precipitation, it was dark," the eye witness described. "Immediately noticed four lights traveling across the sky, from the north heading east or southeast, and gaining altitude. The first 3 lights were in a triangle formation and the 4th light traveled behind the triangle. There was no noise."

The eye-witness is said to have spotted many flying objects in the same night.

"I then witnessed light after light come off the horizon from the north and travel the same pattern, the same speed, probably about 12 more lights total. Some came off the horizon at a constant rate, I would guess they were about 30 seconds apart from each other and seemed to be equidistant from each other coming one-by-one. Others came out perhaps at a 45 or 60 second interval. All lights traveled at a constant speed, at the same speed as the other lights, and all traveled on the same linear path and seemed to eventually disappear."

The triangle-shaped object found over Andover skies has now stirred up a public debate on YouTube, but some skeptics believe the UFO is probably only a drone, controlled by a pilot on the ground.

Check out the video here: