Police say 17-year-old Mitchell Silverstein stabbed another 17-year-old in the chest Thursday night in Winnetka following an argument over a stolen i-phone.
Silverstein will be tried as an adult.
The victim's father, who requested his name not be used, talked about the injuries his son suffered during the attack.
"He's going to be okay," he said. "He has a collapsed lung. He's recovering. It's a serious injury. He could've been killed actually, quite easily. A few inches more, you know, towards his heart. But it was a blade about that long, right in there."
A 16-year-old who tried to help the victim was stabbed in the hand.
Both victims are expected to be okay.