An explosion reportedly damaged a power plant in the Iranian city of Ahvaz on Saturday, the latest in a series of mysterious blasts in the country that prompted Iran to issue a warning to Israel and the US earlier this week.

Persian and Arabic media reported an explosion and fire at the Zargan power plant in Ahvaz in Iran’s southwest, near the Persian Gulf and the Iraqi border.

Videos posted online showed a column of smoke at the facility and workers filing past a fire truck.

Iran’s IRNA news agency later reported that the fire at the plant had been brought under control. It said the blaze was ignited when a transformer exploded.

Mohammad Hafezi, the power plant’s health and safety manager, told IRNA the cause of the fire was under investigation.

A few hours later on Saturday, IRNA said a chlorine gas leak at a petrochemical center in southeast Iran sickened 70 workers.

Most of the workers at the Karun petrochemical center in the city of Mahshahr in southeast Khuzestan province were released after undergoing medical treatment.

The two incidents came after an explosion damaged Iran’s Natanz nuclear facility on Thursday, and last week a large blast was felt in Tehran, apparently caused by an explosion at the Parchin military complex, which defense analysts believe holds an underground tunnel system and missile production facilities.

An Israeli TV report Friday night said that Israel was bracing for a possible Iranian retaliation as officials in Tehran suggested on Friday that the mystery fire and explosion at Natanz could have been caused by an Israeli cyberattack.

The report said the attack “destroyed” a laboratory where Iran was developing advanced centrifuges for faster uranium enrichment, and a Kuwaiti report quoted an unnamed source assessing that the strike set back the Iranian nuclear program by two months.

Three Iranian officials told the Reuters news agency they believed the incident at the Natanz enrichment facility early Thursday was the result of a cyberattack, and two of them said Israel could have been behind it, but offered no evidence.

Asked about reports of the incident at a press conference Thursday evening, Prime Minister Benjamin Netanyahu brushed aside the question: “I don’t address these issues,” he said.

But Amos Yadlin, the head of the Institute for National Security Studies, and a former head of IDF military intelligence, tweeted Friday that, “According to foreign sources, it appears that the prime minister focused this week on Iran rather than [his plan for West Bank] annexation. This is the policy I’ve been recommending in the last few weeks.”

Added Yadlin: “If Israel is accused by official sources then we need to be operationally prepared for the possibility of an Iranian reaction (through cyber, firing missiles from Syria or a terror attack overseas).”

Officially, Iran reported an “accident” occurred Thursday at the Natanz nuclear complex in central Iran, saying there were no casualties or radioactive pollution. But top generals also said Iran would respond if the incident turned out to be a cyberattack.

Israel’s Channel 13 TV military analyst Alon Ben-David said Friday evening that the attack hit “the facility where Iran develops more advanced centrifuges — what are meant to be the next stage of the nuclear program, to produce enriched uranium at a far faster rate. That facility yesterday took a substantial hit; the explosion destroyed this lab.

“Those were centrifuges that were supposed to be installed underground at the Natanz facility; they were intended to replace the old centrifuges and produce a lot more enriched uranium, a lot more quickly,” he added. “They suffered a blow. It has to be assumed that at some stage, they will want to retaliate.”

Ben-David said Israel was “bracing” for an Iranian response, likely via a cyberattack. In an April cyberattack attributed by western intelligence officials to Iran, an attempt was made to increase chlorine levels in water flowing to residential Israeli areas.

Hours after the Natanz fire and reported explosion on Thursday, Iran’s state news agency IRNA published an editorial warning that “if there are signs of hostile countries crossing Iran’s red lines in any way, especially the Zionist regime (Israel) and the United States, Iran’s strategy to confront the new situation must be fundamentally reconsidered.”

IRNA also reported that unnamed Israeli social media accounts had claimed the Jewish state was responsible for the “sabotage attempts.” It stressed that Iran had tried “to prevent escalations and unpredictable situations while defending its position and national interests.”

Natanz, located some 250 kilometers (155 miles) south of Tehran, includes underground facilities buried under some 7.6 meters (25 feet) of concrete, which offers protection from airstrikes.

There was “no nuclear material (at the damaged warehouse) and no potential of pollution,” the spokesman for Iran’s Atomic Energy Organization Behrouz Kamalvandi told state television.

Kamalvandi said no radioactive material or personnel were present at the warehouse within the Natanz site in central Iran, one of the country’s main uranium enrichment plants.

The Iranian Atomic Energy Organization released a photo purportedly from the site, showing a one-story building with a damaged roof, walls apparently blackened by fire and doors hanging off their hinges as if blown out from the inside.

The Fars news agency, which is close to the country’s ultra-conservatives, initially reported that the Parchin blast last week was caused by “an industrial gas tank explosion” near a facility belonging to the defense ministry. It cited an “informed source” and said the site of the incident was not related to the military.

However, this was largely disregarded by defense analysts as satellite photographs of the Parchin military complex emerged showing large amounts of damage at the site.

Later, Iranian Defense Ministry spokesman Davood Abdi blamed the blast on leaking gas that he did not identify and said no one was killed in the explosion.

Satellite photos of the area, some 20 kilometers (12.5 miles) east of downtown Tehran, showed hundreds of meters (yards) of charred scrubland not seen in images of the area taken in the weeks ahead of the incident. The building near the char marks resembled the facility seen in the state TV footage.

The gas storage area sits near what analysts describe as Iran’s Khojir missile facility. The explosion appears to have struck a facility for the Shahid Bakeri Industrial Group, which makes solid-propellant rockets, said Fabian Hinz, a research associate at the Middlebury Institute of International Studies at Monterey.

The Washington-based Center for Strategic and International Studies identified Khojir as the “site of numerous tunnels, some suspected of use for arms assembly.” Large industrial buildings at the site visible from satellite photographs also suggest missile assembly being conducted there.

Iranian officials themselves also identified the site as being home to a military base where the International Atomic Energy Agency previously said it suspects Iran conducted tests of explosive triggers that could be used in nuclear weapons.

Iran long has denied seeking nuclear weapons, though the IAEA previously said Iran had done work in “support of a possible military dimension to its nuclear program” that largely halted in late 2003.

Western concerns over the Iranian atomic program led to sanctions and eventually to Tehran’s 2015 nuclear deal with world powers. The US under President Donald Trump unilaterally withdrew from the accord in May 2018, leading to a series of escalating attacks between Iran and the US, and to Tehran abandoning the deal’s production limits.