Most of the workers at the Karun petrochemical center in the city of Mahshahr in southeast Khuzestan province were released after undergoing medical treatment Meanwhile, in the city of Ahvaz, also in Khuzestan, a fire at the Zergan power plant was ignited when a transformer exploded TEHRAN, Iran: A chlorine gas leak at a petrochemical center in southeast Iran sickened 70 workers, state-run IRNA news agency reported Saturday. Most of the workers at the Karun petrochemical center in the city of Mahshahr in southeast Khuzestan province were released after undergoing medical treatment. Meanwhile, in the city of Ahvaz, also in Khuzestan, a fire at the Zergan power plant was ignited when a transformer exploded, IRNA reported Saturday. The blaze was contained by firefighters after two hours of battling the blaze. Mohammad Hafezi, the power plant’s health and safety manager, told IRNA the cause of the fire was under investigation. The two incidents in Iran’s oil-rich Khuzestan come after a fire and explosion at a centrifuge production plant above Iran’s underground Natanz nuclear enrichment facility early Thursday. Officials said the cause of the fire at Natanz is known to officials, but won’t be immediately released for “security reasons.” On Tuesday, an explosion from a gas leak in a medical clinic in northern Tehran killed 19 people.