WELLINGTON, Colo. (AP) - Federal authorities are investigating safety procedures at a northern Colorado farm after nine workers were struck by lightning. Two of the workers in the organic fields in Wellington were critically injured when the lightning struck Thursday afternoon. The Fort Collins Coloradoan (http://noconow.co/18xxole ) reported Tuesday that Denver's Federal Occupational Safety and Health Administration office is investigating. Herb Gibson, the director OSHA's Denver office, says the agency doesn't have any regulations that address lightning strikes. He said the office will review what policies and procedures the farm workers were supposed to follow.