Northern WA residents have spent the weekend puzzling over sightings and photographs of what appeared to be a fireball hitting the Earth — a mystery police believe they have now solved.

On Saturday night, residents across the Gascoyne and Pilbara reported seeing a fireball with a long tail moving across the sky.

Among the witnesses was Danielle Mautama, who was travelling with her family on a back road in Karratha.

"It was moving really quickly across the sky," she said.

"We originally thought it was a shooting star, but it had blue and green colours. And then we thought maybe fireworks, but the path didn't look like fireworks, because it was going horizontally.

"So we came home and saw online that other people had seen or heard things as well, and now we are super curious about what it was."

Later that night, Chris Topher from Port Hedland took a photograph of what appeared to be the fireball crashing to Earth.

Mr Topher's photo was taken just minutes after witnesses reported seeing what appeared to be a fireball move across the sky. ( Supplied: Chris Topher )

Mr Topher told the ABC he and his son were at the go-kart track on the outskirts of town when they spotted the fireball moving quickly across the night sky.

"My son was getting out of his go-kart and looked up and said, 'Oh what's that Dad?'" he said.

"It looked like fireworks coming down, but it had a big long tail on it, and purpley-green colours coming off it.

"Then it went out just before it hit the ground ... and about five minutes later there was a fire just where it landed."

Mr Topher's photo, with its bright white light and glowing smoke, led many to conclude the mysterious aerial object had plummeted to Earth.

But when ABC News contacted the South Hedland police station, officers said they had had no reports of fireballs, space junk, or fires.

An X-Files-style investigation ensued through Sunday afternoon, with police inspecting the site and interviewing the witnesses.

They concluded that the photograph showed something far more banal than an outer space fireball.

The burnt out car wreck that police say was mistaken for a meteorite or space junk fire. ( Supplied: South Hedland Police )

Acting Sergeant Darren Royle said the bright white light and smoke was a burning car wreck.

"The car appears to have been set on fire about 300 or 400 metres behind the go-kart track, and it's just a coincidence that that was a few minutes after people there saw something in the sky," he said.

"So the fire was caused by a burning car wreck."

But what was the night-time fireball, seen by at least half a dozen people in different locations in the Gascoyne and Pilbara? The mystery remains.