Officials believe that those boats had been winterized. A plug in those boats had been removed so those boats began to take on water.
Authorities say two boys were on one boat when it quickly sank because the bottom plugs in the boat had been removed. Police say another teen jumped in to try to save them, and all three drowned.
Authorities later removed the bodies of the three teens from the river. The students were identified as 17-year-old Melvin Choice Jr., 18-year-old Jimmie Avant and 16-year-old Adrian Jones. Authorities say the river's swift currents and debris made it difficult to recover the bodies.
Investigators were trying to figure out the sequence of events that led up to this tragedy.
"It's hard, you know, 18, he's 18 years old. And he did everything right," said Leonard Avant, victim's father.
Parents comforted one another as divers found the first body. The first victim was discovered just after daybreak and nearly five hours after the paddle boats the boys were on sank.
"I'm a little bit disturbed. I'm here to see my son. He called me. Of course, he's upset because he couldn't save the young men that was drowning," said Pastor Robert Williams, the father of a survivor.
Pastor Williams says his 18-year-old son, Marshaun, tried to save his North Lawndale College Prep classmates after several of them decided to take paddle boats onto the Fox River around 1 a.m. Friday, apparently without the approval of school chaperones who were staying in the retreat dorm.
"They are given a set of rules. I do not know exactly what was said to them from their teachers," said Linda Fauser, YMCA.
Witnesses say it was moments after the boats were on the river that they began to take in 42-degree water.
"There is a decent current underneath the surface. The divers are having a hard time. They are equipped and trained to swim in this kind of environment. It's definitely difficult. They would have had a hard time," said Julie Didier, Algonquin-Lake in the Hills Fire Protection District.
Relatives say the teens were part of a group of 31 students at Camp Algonquin for an eight-day leadership retreat that was supposed to end Friday.
"He was a real likable person. He was the comedian of the family. He would always crack jokes and make everybody laugh. He loved to dance a lot. And he was very athletic," said Chiquita Lee, victim's sister.
As victims' families coped with the tragedy, investigators were trying to sift through the moments that led up to the accident.
"It's a boat accident investigation, similar to a traffic accident. It needs to be investigated to find out what did occur and what caused this accident to happen," said Sgt. Brett Scroggins, Illinois DNR Conservation Police.
Authorities say the group had been to Camp Algonquin once before, in August 2007, without any incident.
Students and school officials cope with the news
"As best we can, try to help them deal with it. The administrators at the school are meeting this afternoon to talk about what takes place next week, how they get through the next few days," said Rufus Williams, CPS board president.
A rainy Friday morning matched the mood outside North Lawndale College Prep high school. Word of the tragic accident involving the three schoolmates spread quickly as students and faculty arrived. Many students comforted each other and fought back tears as they remembered their three friends.
"They were good students. They keep everyone laughing, smiling. I just can't believe they're gone," said student Andrewniqua Halls.
"This is a real family; NLCPS is real family. This just shows that, even though it's something bad, it actually brought a lot of family together," said Johnathan Boyce, another student.
"I want him to be remembered so much. He was a good student, top 10, track star. He was on basketball team. He will be remembered," said student Jasmine Boyce.
School officials say 31 boys from the high school were on the week-long retreat, along with 10 adult supervisors. The three boys involved in the accident were said to be among the top students at a school, where officials say 100 percent of the students graduated.
Many of the students were dismissed early from class Friday. Those who were staying were working with CPS grief counselors.
School officials say they are not involved in the ongoing investigation. They say they are now focused on comforting the students.
"Our main concern is taking care of students. Take it one second at a time. It's a community. That's what's going to get us through," said Dr. Robert Karpinski, co-principal.
"Our counselors are highly qualified. We're just comforting each other right now," said North Lawndale College Prep Co-Principal Lacael Pratt.
The Associated Press contributed to this report.