Police in Aberdeen and Inverness say they have been receiving a large number of calls about flash over northern Scotland.
There is speculation it could have been a meteor burning up in the atmosphere or may have been a sonic boom.
Some reports suggested it may have been seen as far south as Edinburgh.
Highland councillor Ken Gowans said that he had witnessed the flash. “I was standing in my upstairs room on the phone, blethering away and the next thing there was this big flash. It was a fair size, and a light, greeny colour.”
“I phoned the police. They said they had received numerous reports of it. It was almost due south from where I am in Westhill. This thing was massive.”
Police were unable to say what was behind the incident, speculating that it may have been a natural phenomenon.
Jenni Morrison who posted video of the lights on her dashcam as she drove on the A944 heading towards Alford, outside Aberdeen said: I saw this on my way home. It lit up the sky like a light switch had gone on. Amazing.”
A Police Scotland source said they were unable to ascertain what had happened.
A spokesman for the force said: “We’ve had reports of a very loud bang but we’ve been unable to establish what it is.
“Some people were saying their houses were shaking.”
He said there had been no reports of aircraft in distress in the area from air traffic control.