An Israeli missile reportedly struck a site in Iran late Thursday night (early Friday morning local time), multiple U.S. officials confirmed to several media outlets. Citing an unnamed senior U.S. official, two unnamed U.S. officials, and an unnamed U.S. official, respectively, and reported that Israeli officials had warned U.S. officials earlier on Thursday that Israel planned to attack Iran within the next 24-48 hours.

Details of the strike, including its exact location and the extent of the damage, remain unclear. FARS, a news agency managed by the Iranian military, reported that the attack happened near Isfahan—a city some 340 km. south of Tehran that hosts key military sites, including a major airbase and nuclear facilities. It reported that the nuclear facility is completely safe, according to “informed sources.”

Iranian state-affiliated news agency IRNA reported that Iran’s air defense system had been activated in the skies of several provinces, following explosions heard in and around Isfahan. The source of the explosion was a “defense shot,” fired after defense forces saw a “suspicious object,” IRNA stated. Flights to Tehran, Isfahan, and Shiraz were disrupted.

The apparent attack comes just days after Iran launched hundreds of drones and missiles at Israel over the weekend, most of which were intercepted by Israel’s defense systems as well as those of its allies and partners. The weekend attack sparked widespread fears of a sharp escalation, as regional tensions have heightened amid Israel’s war in Gaza. As world leaders urged Israel to refrain from a counterattack, Iran, which said the drone strike was a retaliation to an Israeli strike on its Damascus consulate on April 1, said that it considered the matter “closed.”

Iranian foreign minister Hossein Amir-Abdollahian stated earlier on Thursday that “in case the Israeli regime embarks on adventurism again and takes action against the interests of Iran, the next response from us will be immediate and at a maximum level.”

This is a developing story and will be updated.