The photographs and sighting are being investigated by the Mutual UFO Network (MUFON) after it received a report from an eyewitness.
The witness, who has not been named, said: “I looked up to see what I first thought was a passenger plane on fire.
“Within a second or two, I was startled because I had realised this was no plane.
“It was a dull silver-domed object with orange lights around its middle.
“It was a typical domed UFO looking craft.
“It was obvious to me that this craft was in trouble.”
The witness said there was no flame or intense burning, but some sort of vapour trail being left.
They added: “The vapour trail didn’t seem to be coming from any particular vent or place on the craft, it seemed to almost enshroud the craft and then slip off and fall behind. It would leave a trail and dissipate within a few seconds.
“The colour was both concerning and fascinatingly beautiful.
“My first thoughts were that it was highly poisonous or radioactive.
“The rumbling hiss seemed to increase in intensity coinciding with the billowing emerald green shimmery misty vapour or smoke this craft was leaving in its wake.”
The sighting happened around 11am on July 20 2013 in Huntington Beach, California, USA, but has only just been reported to US-based MUFON, which keeps a global database of UFO sightings.
The witness believes it was about a mile away, travelling south or south west, and the object was the size of a school bus at about 35 to 40 feet wide.
The report added: “I became so overwhelmed with emotion upon seeing this object that I remember feeling very faint, and close to throwing up my breakfast.”
It was then that they rattled off three pictures as it travelled from right to left towards the coast.
Before MUFON has released any view on the sighting, it has been picked up by online UFO sites.
Scott C Waring, editor of ufosightingsdaily.com, said he did not believe the UFO was crashing.
He blogged: “A dark UFO disk was moving around above the eyewitnesses neighbourhood and the UFO was making a green trail behind it.”
He then went on to reveal an outlandish theory.
He said: “Now this concerns me because it appears to be a UFO that is spraying something over the neighbourhood.
“This may be another alien experiment… something that will effect their health, probably mental health and either improve or worsen their lives. If this UFO was damaged which caused the smoke, it would have landed somewhere.”
Just yesterday, Mr Waring claimed alleged corrupt global leaders known as the Illuminati were spraying drugs onto populations through aircraft contrails to make people ill because of vested interests in pharmaceutical companies.
Fortunately, Mr Waring is known for speculating on UFO sightings to reveal crackpot theories, for which he offers no evidence to support them.