An explosion occurred on Tuesday at the site of the Toprash oil refinery in the eastern Istanbul city of Izmit, Turkey’s largest oil refinery, during what Turkish media described as planned drilling work, with no reports of injuries, the local mayor told NTV.

The fire at the northwestern site was under control, Kocaeli provincial mayor Tahir Buyukakin said, adding that authorities had received no reports of injuries.

Television footage showed smoke billowing from the site near Istanbul.