Bengaluru residents were jolted by a deafening burst on Wednesday afternoon. The puzzled residents took to social media to share their experience of tremors and rattling of windowpanes for about nine seconds around 1.20 pm. However, there were no calls to the police control room reporting any damage, reported NDTV.

Around 9.30 pm, the defence ministry provided some clarity on the incident. It sound turned out to be the sonic boom of a test aircraft.

“It was a routine IAF Test Flight involving a supersonic profile which took off from Bluru [Bengaluru] Airport and flew in the allotted airspace well outside City limits,” Spokesman for the Ministry of Defence, Bengaluru, tweeted. “The aircraft was of Aircraft Systems and Testing Establishment (ASTE) whose Test Pilots & Flight Test Engineers routinely test out all aeroplanes. The sonic boom was probably heard while the aircraft was decelerating from supersonic to subsonic speed between 36,000 and 40,000 feet altitude.”

In another tweet, the ministry spokesperson clarified that the aircraft was far away from the city limits. “The sound of a sonic boom can be heard and felt by an observer even when the aircraft is flying as far away as 65 to 80 kilometres away from the person.”

The sound was heard across Marathahalli, areas around the Hindustan Aeronautics Ltd. Whitefield, Electronics City, Fraser Town, Kammanahalli, Sarjapur, the football stadium, and Ulsoor in the east; Bannerghatta Road, MG Road, Jayanagar, and JP Nagar in the south, among other areas.

IAF’s Headquarters Training Command based in Bengaluru said no aircraft of training command was flying in the area, reported The Hindu. “However, ASTE and HAL [Hindustan Aeronautics Limited] could have been undertaking their routine test flying, which necessitates going supersonic at times,” it added. “These are done well beyond the city limits in specified sectors. However, considering the atmospheric conditions and reduced noise levels in the city during these times, the aircraft sound may become clearly audible even if it happened way out from the city.”

Earlier in the day, officials of the State disaster monitoring agency dismissed initial fears of an earthquake. “The seismometers did not capture any ground vibrations as generally happens during a mild tremor,” tweeted the Karnataka State Natural Disaster Monitoring Centre. “The activity is purely a loud unknown noise.”