The blaze, called the Mullica River fire, had burned about 12,000 acres in Wharton State Forest and had been reduced by 70 percent since Monday night, officials said. The forest, in South Jersey, is located about 30 miles northwest of Atlantic City. No injuries were reported, but 18 structures, including several farms and camps, were threatened by the fire, officials said. They also said they had ruled out natural causes in their investigation. “I think it’s important to think about the fact that most of our forest fires are caused by humans,” Shawn LaTourette, New Jersey Environmental Protection Commissioner, told a news conference Monday. He noted that illegal fires that have not been completely extinguished are a danger. Gov. Phil Murphy said on Twitter that he was grateful for the crews who worked around the clock to contain the fire. While the weather was dry and sunny on Monday, temperatures were forecast to be slightly above average on Tuesday and humidity was rising throughout the region. More rain was expected on Wednesday. The fire was first spotted Sunday morning, but immediate efforts to contain it were ineffective due to its remote location, which was difficult to access, said New Jersey Chief of Staff Gregory McLaughlin during the meeting. on Monday. In the Western United States, fires increase in size and intensity, and fire seasons grow. Recent research has shown that the heat and dryness associated with global warming are the main reasons for the increase in larger and more powerful fires. The peak of the fire season in New Jersey is from mid-March to May, according to the state Department of Environmental Protection. About 7,000 acres of the state’s forests are destroyed or destroyed each year by an average of 1,500 fires. The Warren Grove fire in May 2007 was one of the largest forest fires in state history, destroying more than 17,000 acres and destroying four homes. This fire was caused by flares fired by a pilot of the National Guard. Aerial video of the Mullica River fire on Monday showed dense smoke rising from above the forest. Miles off the coast of Jersey, some seafarers told ABC 6, a Philadelphia television station, that they saw hazy conditions, with one woman saying it smelled like “hyperactive barbecue smoke.” At least one man reported seeing ashes in his vehicle.