A sheriff’s dispatcher says there has been an explosion at an oil rig in Oklahoma, but there have been no confirmed injuries. Beth Massey of the Blaine County Sheriff’s Department tells The Associated Press officials have formed a perimeter around the rig near Watonga, about 80 miles northwest of Oklahoma City. She had no further details about the explosion, which happened late Monday night. Watonga Assistant Fire Chief Verlen Bills tells the Oklahoma City Oklahoman that the cause of the blaze wasn’t known. Several homes within a mile of the rig were evacuated.