(CNN) Despite an "exhaustive investigation," the US Forest Service announced Friday the cause of the largest single fire in California's recorded history is undetermined. Lightning is the most probable cause of the wildfire, but authorities aren't ruling out arson or "smoking activities," fire investigators said in a news release. The undetermined status is "not uncommon given the complexities involved," officials said in a news releaseOfficials excluded many potential causes such as equipment use, escaped campfire, activities by children and burning debris. Despite some speculation, officials also said there were "no illegal marijuana grow sites nearby, so that also was excluded as a possible cause." Fresno County officials said the cost of fighting and extinguishing the fire was $193 million.

Source: CNN July 17, 2021 01:07 UTC