The fire department was called to the scene just after 5 p.m. Tuesday.
Lifeguards and paramedics gave the boy CPR as stunned beach goers looked on. He was rushed to Lurie's Children's Hospital in critical condition but died late Tuesday night.
"When we seen the splash, the lifeguard came from the pier and he ran, telling everyone to get out of the water," said Mayesha Brown, witness.
A park district spokeswoman says the boy was at North Avenue Beach with two other teens. They told lifeguards they couldn't find their friend and had last seen him in the water.
Witnesses say the boy was spotted 30 to 50 yards off shore and in trouble.
"He was definitely just way too far out there," said Nani Romero, witness. "When I started noticing him you could see they were right there at the line where all the posts are in the water. The water was just way too rough out there ... There were two people out there trying to help him and the lifeguard jumped out of the boat and helped the two people get him out of the water."
"There was a huge crowd of people over there willing to help, everyone was," said Lisa Carroll, witness.
The Lake Michigan water temperature is near 60 degrees. Paramedics placed the teen in what's known as a hypothermia bag to try to warm him up on his ride to the hospital.
The incident left Alfredo Lopez and his family from Aurora shaken.
"I got two kids, it kind of scared me when they said everyone out of the water because there's a child missing," said Lopez. "So everyone was scared."
The 14-year-old boy has not been identified because family members are still being notified.