An Ontario man faces robbery and firearm charges Monday after authorities say he tried to steal food from a Little Caesars in Ontario with an AR-15-style rifle.Pablito Lucero, 20, was arrested Sunday at the Little Caesars Pizza, 602-B W Holt Blvd. officers were called to the restaurant on the report of a man in possession of a firearm. As officers arrived, they saw a man leaving the restaurant with stolen food items and a large rifle in his shirt, according to Ontario police.The gunman was ordered to put his hands in the air, but when he didn't comply, officers used a stun gun on him, police said. He was taken into custody without any injury to officers or customers."The officers who responded to the call demonstrated exemplary composure while dealing with a high stress situation involving a dangerous suspect in possession of multiple firearms," Ontario police said in a statement.Lucero was found to be in possession of an AR-15-style assault rifle and 9mm polymer handgun, police said. He was being held on $100,000 on suspicion of robbery and multiple firearm charges, and is scheduled to appear in court Wednesday.