An earthquake, plane or thunder, what did Bengaluru hear?

BENGALURU: Was it a plane going supersonic, an earthquake, or just cold and warm air colliding that created a loud noise that many parts of southeast Bengaluru heard at around 1.25pm on Wednesday? It could have been any of the three, but authorities so far have ruled out an earthquake officially.
“The activity reported in Bengaluru is not due to an earthquake. The seismometers did not capture any ground vibration as generally happens during a mild tremor. The activity is purely a loud unknown noise,” the Karnataka State Natural Disaster Management Centre (KSNDMC) said.
With the earthquake having been ruled out, another possibility was that a fighter plane went supersonic during an air trial creating a sonic boom, as many people also sighted a plane after they heard the sound. While defence PSU HAL ruled out any of their planes having gone supersonic, the IAF, which is also testing fighters in Bengaluru is yet to respond officially.
“During air trials the profile will include testing for supersonic speed. However, there are clear parametres of how to do it, and if it is indeed from a plane, it would be by mistake,” a former test pilot of the IAF told TOI.
Another source from the KSNDMC quoted an expert and said that it was the likely effect of heavy vacuum created and sudden entry of Cyclonic wind. What this means is that warm and cold air collide, as it happens during cyclones, and create a vacuum. Experts say that it is an atmospheric phenomenon, but not a thunder.
While the second and third theories need to be confirmed, the event itself saw a lot of drama in Bengaluru, both on the ground, and on social media.