Reports of a loud explosion on the north Cornwall and Devon border are being investigated.
The bang was believed to have been a sonic boom
A number of residents reported hearing a loud bang between 1130 and 1200 BST around the Bude and Holsworthy area. Others said their homes were damaged.
Western Power and the British Geological Survey have carried out checks in the area.
Pc Baxter Proven of Devon and Cornwall Police said an investigation was under way into the cause.
He said: "One theory being considering is perhaps a military aircraft has broken the sound barrier a little too close to the land and that has caused this sonic boom and this, in turn, caused some light damage around the north Cornwall area."
One resident in Bude said a crack in her kitchen had widened as a result, and others reported experiencing their properties "shaking".
A BBC Radio Cornwall listener said: "The stables physically shook. It sounded like Concorde used to sound when it broke the sonic barrier. But much louder. It went 'boom, boom'."
Experts ruled out the possibility of an earth tremor
Western Power Distribution said engineers had completed checks and found no faults with its systems.
The Ministry of Defence and the RAF said there were no records of their aircraft flying over the area.
The Civil Aviation Authority said it was also unaware of the cause.
David Galloway from the British Geological Survey said the organisation checked its readings for the area after receiving several phone calls about the bang.
He said: "We've not got any signals at all from any instruments, and in fact we have instruments nearby at Hartland Point."
He added it was possible that it might have been a sonic boom, but although the equipment was geared towards detecting ground movement, it would sometimes pick up such disturbances as well.
He said: "Typically we'd register any ground movement but we have been known to have signals of a sonic nature to register."