The suspect allegedly left a party in the 4300-block of West Potomac, returned with a gun and opened fire.
All the victim's father, Cesar Escalante, could do Sunday was ask why, as he stood just steps away from the place where his only son, Rogger Escalante, was murdered.
Cesar Escalante told ABC7Chicago that his son died while at a friend's house where he had been forbidden to go.
"I had no idea what was going on at the party. He just asked me for permission, and I emphatically said, 'No,'" the father told ABC7 Chicago in Spanish.
But the teen went anyway, after telling both his parents he was going somewhere else.
"I emphatically told him he couldn't go. I was adamant about it in telling not to go because it's a very dangerous area. I work delivering pizzas, and I know the area very well," Cesar Escalante said in Spanish. "I told him no."
Police say officers responded to shots fired at approximately 4 a.m. Sunday.
The teen's friend who hosted the party for about a dozen people says trouble began when a group of uninvited guys showed up and started a fight.
The fight eventually moved outside.
"The next thing you know, the car pulled over and started shooting at us," friend Jose Romero said.
The bullets went through the home's front window.
"After my boy got shot, I tried to revive him, but he wouldn't come back to life, and as soon as the ambulance got here, they declared him as dead already," said Romero.
Rogger Escalante and his family came to this country from Peru four years ago. His family says the Roosevelt High School junior was a good student whose goal was to study computer science.
Sunday afternoon, the teen's father and mother waited for justice.
Cesar Escalante says he hopes anyone with information about the attack that killed his son will contact police.
The two other shooting victims were taken to an area hospital in good condition with minor injuries.
Investigators had not made any arrests Sunday evening and had no one in custody.