(c) Any private person, firm or corporation, and any employee or agent of such person, firm or corporation, who renders assistance or advice at the request of the State, or any political subdivision of the State under this Act during an actual or impending disaster, shall not be civilly liable for causing the death of, or injury to, any person or damage to any property except in the event of willful misconduct. The immunities provided in this subsection (c) shall not apply to any private person, firm or corporation, or to any employee or agent of such person, firm or corporation whose act or omission caused in whole or in part such actual or impending disaster and who would otherwise be liable therefor.