Parisians were rattled Wednesday by what was initially reported as a massive explosion, which was felt across the city.

Emergency lines lit up shortly after the noise and accompanying tremor were recorded at noon, prompting authorities to investigate.

Shortly afterwards, however, Paris police reported that the reverberations were caused by the sonic boom of a fighter jet which had broken the sound barrier.

“A very large noise was heard in Paris and in the Paris region,” the police department tweeted. “There is no explosion, it is caused by a fighter plane which broke the sound barrier.”

The sonic boom shook buildings both in the city and in nearby suburbs, witnesses said, according to a report by AFP.

BFM TV quoted Minister of the Armed Forces Florence Parly as saying that a fighter jet was forced to break the sound barrier in order to carry out an intercept mission, without providing details on the mission itself.