Dozens of people across South East Cornwall phoned police in panic this week to report a loud bang which “shook the earth”.
And scientists say the sonic boom was most likely something from outer space falling to earth.
The UFO – so far assumed to be a meteor – was heard apparently breaking the sound barrier from Dartmoor to Saltash.
People in Millbrook, across the Tamar Valley and the South Hams heard the blast and in South Devon a police station’s doors were blown open.
Inspector Gareth Twigg said: “The first calls reported sounds like an explosion. People also talked about there also being loud noise and then objects shaking.
“A lady from Dartmoor who lived through World War II said it was like a bomb going off.
“In Newton Abbot station, we had windows and the ground shaking, so we felt it first hand too.
“The British Geological Survey told us it was possibly a sonic boom from a meteorite, as that caused pressure changes in the atmosphere while falling.
The director of Cornwall’s Roseland Observatory revealed the day before Devon’s outer space experience, alien matter landed in San Francisco.
And about a month ago there were bangs and tremors in Britain and Canada.
But he explained it was most likely to be spacecraft or satellite debris – or maybe meteors, because the Earth is moving through a trail left by Halley’s Comet.
But Alan Penman of Plymouth Astronomical Society said: “It’s certainly not an asteroid.
“There’ve been several instance recently of pieces of space junk, rocket or satellite remnants falling back to earth and burning up.
“I’d say it was a ‘bolide’ – a big chunk of rock which burns and explode on entering the Earths atmosphere, scattering debris over a large area. They can create a sonic boom.”
Others online wondered if something more exotic might have landed from outer space.
Vanessa Keeling from Newton Abbot posted late on Thursday afternoon: “Heard a massive bang in the sky, never heard anything like it.
“Now they’re saying something’s landed from outer space – will be looking out for strangers in town!”
And Keith Pope from Saltash said: “This is it guys – 2012 and all that – they’re coming for us!”
Nobody’s found any bits of space-rock yet so if you turn up anything on your travels – let us know! Just post below!