425 ILCS 40/9

While engaged in controlling or extinguishing forest fires, any forest fire warden may enter upon the lands of any person, firm, private or municipal corporation or the State of Illinois to carry out his duties. He may set backfires, cut fire lanes and employ any other customary and accepted method of suppressing and extinguishing forest fires. Forest fire wardens or other persons employed by the Department for the purpose of extinguishing and suppressing forest fires shall not be personally liable for any act required or permitted to be done under the provisions of this Act, while acting within the scope of their duties, unless such actions causing injury are maliciously and wilfully or wantonly inflicted.