The cause of an explosion that rocked an Iranian city that houses a key nuclear facility remains unclear.
Monday's explosion in Isfahan reportedly caused windows to shake throughout the city.
The local government told news agencies that the explosion was part of a military drill. Some news agencies said the explosion came from a gas depot.
The Isfahan uranium conversion plant is supervised and frequently visited by the United Nation's nuclear watchdog, the International Atomic Energy Agency.
Earlier this month, an explosion at an Iranian ammunition depot killed Gen. Hasan Moghaddam and 16 other Revolutionary Guard members. Israel's Mossad intelligency agency was suspected in that blast.