VIDEO: Thick, black smoke could be seen for miles after a transformer at a Providence power plant caught fire Saturday. The explosion happened around 11 a.m. at the Manchester Street Power Station by the Port of Providence. About 5,000 gallons of mineral oil burned, Providence Fire Deputy Chief Brian Mahoney said. “There are five very large radiators on the transformers. That’s the oil they use to keep the transformers cool,” Mahoney said. The transformer was in the yard next to the building. National Grid also runs a facility on the property, but spokesperson Ted Kresse said no National Grid equipment was damaged. “This particular plant has a skeleton crew that works in the plant. There was never any danger of the plant itself catching fire,” Mahoney said. Before firefighters could contain the flames, National Grid had to shut off power. Around 115,000 volts of electricity run through the property, Mahoney said.