Update (094 EST): Local news are reporting that previous reports documenting an explosion at the military facility were false and that a civilian excavation contractor was detonating controlled explosives in support of construction operations.
At 0730 EST, a large explosion rocked the area near the Parchin military and nuclear testing facility near Tehran which is governed by the Iranian Revolutionary Guards Corps. Few details have emerged so far and no casualties have been reported. This is developing.
Parchin Military Complex is located approximately 20 kilometers southeast of downtown Tehran. The IAEA was given access to Parchin on 1 November 2005, and took environmental samples: inspectors did not observe any unusual activities in the buildings visited, and the results of the analysis of environmental samples did not indicate the presence of nuclear material. Parchin is a facility for the testing and manufacturing of conventional explosives; IAEA safeguards inspectors were looking not for evidence of nuclear material, but of the kind of explosives testing consistent with nuclear weapons research and development. In November 2011, the IAEA reported that it had “credible” information that Parchin was used for implosion testing. The IAEA sought additional access to Parchin, which Iran did not grant. (Wiki)
An explosion rocked the facility in May of 2022 which killed an engineer and was attributed to Israeli sabotage.