A massive fire in northern Minnesota has destroyed a heating oil and fuel company near the Canadian border. Rainy Lake Oil Co. erupted in huge plumes of fire, fueled by eight or nine tanks inside the company's warehouse near International Falls.The local fire department says the cause of the fire is under investigation.The company's office manager, Janelle Heem, says a warehouse, office and gas station were destroyed. She says the company was talking with suppliers Tuesday in order to get the business back on track.