Investigators said the child, who family identified as Onyx Torres, was playing in waist-deep water at about 4:50 p.m. near the Portage Lakefront and Riverwalk. When he entered a deeper area, a current pulled him from shore.
A family member tried to save him, but the current was too strong.
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Torres was found near Ogden Dunes about 20 minutes later. He was taken to Northwest Health-Portage hospital, where he died.
An autopsy completed Friday morning showed his cause of death was accidental drowning.
His mother, who was not at the lakefront Thursday, is devastated, and has a lot of unanswered questions.
She said her son just finished first grade at Smyser Elementary School in Portage Park, was incredibly smart, loved cars and building things and was the type of kid who brought flowers to his teachers at school.
"He'd hold the door open for me. When, if I'd open my own car door he'd be like, 'Mommy, I gotta be a gentleman. Remember, I've got to practice chivalry,'" said mother Natacha Cruz.
Both parents said their son had the brightest of futures ahead of him.
"I never imagined he was going to, you know, we'd have to bury him, you know. I expected him to grow up to become a man, and..." said father Xavier Cruz.
"We had plans," Natacha Cruz said. "He had seven years, seven years. It wasn't enough. I know my son would have been really successful. He even told me, 'Mommy, I'm going to go to college. I'm going to be an engineer.'"
Onyx loved cars and, even at his young age, was a whiz at building things. Now his loved ones are spreading a critical message.
"Check the weather. Put a life jacket on even if your kid knows how to swim," Natacha said. "Hold your babies tight. Keep a close eye on them."
A GoFundMe for the child's funeral expenses had raised over $11,000 as of Friday night.