On Monday at around 14:50, a loud bang, that sounded like an explosion, took some people in the greater Lausanne region by surprise, prompting a number of them to call the police.
The sound came from a military aircraft breaking the sound barrier, according to various newspapers, including 20 Minutes.
The Swiss military reported that two F/A-18 aircraft took off from its airbase in Emmen in the canton of Luzern in pursuit of a private aircraft that had lost radio contact. The loud bang came from one of the jets breaking the sound barrier.
The sound barrier is the sudden increase in aerodynamic drag experienced by an aircraft when it approaches the speed of sound – the speed of sound is 1,234 km/h.
The Swiss military gave no further details of the operation, which it said was completed without any problems.