Tehran explosion
A major explosion outside Tehran has triggered speculations of an attack against an army base or a research site, but the Iranian military says it was an incident at a gas storage facility.

The blast did not take place at a military site, a defense ministry spokesman, Davoud Abdi, told state TV late Thursday night, adding that the blaze was quickly taken under control and that there were no casualties.

According to a number of reports in state and semi-official media - citing both Abdi and the public relations manager of Tehran emergency, Mir Shahabuddin Ghavami - no emergency services or ambulances were requested in the area following the blast.

For hours, details of the incident remained a mystery, fueling speculations and conspiracy theories, as Iranian TV reported only that the authorities were "investigating the bright light and loud sound" near Tehran.

Rumors initially said the explosion took place at a power station in Sarkh Hasar, east of Tehran, and that similar explosions took place in Shiraz, in southern Iran, prompting further speculation of a cyber attack.

Others suggested an explosion at an ammunition depot in Paradis, citing Islamic Revolutionary Guard Corps (IRGC) chatter on the messaging app Telegram.

New York Times journalist Farnaz Fassihi cited reports that the explosion happened in Parchin, "a military base where Iran has conducted nuclear activity."

Another clip shows a fireball briefly turning the night sky red.

A video shared by researcher Babak Taghvaee includes coordinates of a location in Paradis, where the explosion was filmed.

Others have said the blast took place at Khojir, not Parchin, pointing to a missile production and testing facility there as the possible culprit.

The explosion happened around 2am local time, just half an hour after US Secretary of State Mike Pompeo tweeted about new US sanctions against Iran.