Officials say fear spread among people living near the coast of Sri Lanka's captial as the sound of fighter jets was mistaken for an explosion.
Police initially said there had been an explosion about nine miles from Colombo, and that it had been caused by a sea mine planted by Tamil Tiger rebels.
However, the government later said the sound had been caused by "a sonic boom" from fighter jets on a training run.
In recent months, there has been a surge of violence in Sri Lanka which also added to the fears.
Police initially said Friday's explosion occurred near a site where they had arrested five suspected Tamil Tiger rebels last week.
The rebels were apparently wearing diving gear and planting sea mines.
The defense ministry clarified that people had panicked on hearing "sonic booms released by aircraft under training."
A sonic boom can be heard when an aircraft exceeds the speed of sound.
