A North Dakota oil well owned by Oasis Petroleum Inc blew out over the weekend and has yet to be capped, leaking more than 67,000 gallons of crude so far and endangering a tributary of the Missouri River, state officials said. The cause of the blowout remains unknown, though state officials surmise it may have been caused by hydraulic fracturing of a nearby well in a situation referred to in the industry as "communication" between wells.