TEHRAN, Iran (AP) — A fire broke out Sunday at an oil rig in southern Iran, killing at least two workers just days after another fatal fire at an oil refinery, state television reported.

The brief report did not offer a cause for the blaze near the town of Omideih, some 900 kilometers (560 miles) southwest of the capital, Tehran. It said rescuers had been deployed to the fire, which was so big that helicopters needed to be used to fight the flames.

State television earlier reported four workers had been killed. It did not immediately explain the discrepancy in the death toll. The state-run IRNA news agency said four workers were killed.

The oil rig is located in Iran's Rag-e-Sefid oil field, which produces some 180,000 barrels of oil a day.

Sunday's fire comes after a fire at an oil refinery in Tehran killed seven workers. A cause for that blaze also has not been released.

In 2016, a series of fires at Iranian petrochemical plants and facilities raised suspicions about hacking potentially playing a role, with authorities saying that "viruses had contaminated" equipment at several of the affected complexes.

Iran officially insisted the six known blazes over the span of three months weren't the result of a cyberattack. However, the government acknowledgment of supposedly protected facilities being infected points to the possibility of a concerted effort to target Iranian infrastructure.

Iran's aging oil pipelines and plants, hit hard by years of Western sanctions, have seen a rapid push to increase production following the nuclear deal with world powers that lifted sanctions in return for the curbing of Tehran's nuclear program. Iran also faces occasional separatist attacks on its pipelines.