A volunteer firefighter was arrested on Long Island on Tuesday after the Suffolk County police said he intentionally set a fire in a wooded area, at a time when New York State is seeing a jump in brush fires and wildfires amid dangerously dry conditions.

The man, Jonathan E. Quiles, 20, said in a written statement that he had lit cotton balls on fire and kicked them under a Chevrolet sedan in Medford, N.Y., according to court documents. The car and the debris around it were set ablaze, in one of several brush fires reported in the area on Tuesday.

Mr. Quiles, a volunteer with the Medford Fire Department, was charged with second-degree reckless endangerment and fourth-degree and fifth-degree arson. He pleaded not guilty in a Central Islip courtroom on Wednesday.

He was placed on supervised release with GPS monitoring, according to the Suffolk County district attorney’s office. He is due back in court on Monday.

Mr. Quiles has also been suspended from his position with the Medford Fire District, according to a letter posted on the department’s Facebook page, which said that he would be fired if convicted.

In the letter, Craig G. Cowell, chairman of the fire district, said firefighters were put through arson background checks, and that the department had not had reason to believe that Mr. Quiles “had any inclination of intentionally setting fires.”