So far there have been no reports of injuries, as emergency services and firefighters battled to contain the flames.

The head of Tehran’s Provincial Crisis Management Office said that “a leak at a liquid gas pipeline at the facility sparked the fire,” Reuters reported. The cause of blaze will be investigated, Mansour Darajati added, according to Reuters.

No casualties have been reported at the scene, Shaker Khafaei, the head of public relations of Tehran Oil Refining Co., which runs the refinery, told state news agency IRINN. Khafaei also ruled out the possibility of sabotage.

Videos posted on social media Wednesday showed thick smoke circulating in the southern areas of the Iranian capital.