WINTER PARK, Fla. (AP) — An 11-year-old Florida boy died just days after a sprained ankle led to a flesh-eating bacterial infection, family members said.

Jesse Brown, a fifth grader at Lakemont Elementary School in Winter Park, was injured while using a treadmill last month, his cousin, Megan Brown, told local news outlets. Winter Park is located just north of Orlando.

Megan Brown said the family noticed the boy’s leg was covered in reddish-purple bruises a few days after the accident and that the bruises were the first sign of strep-A. She said the bacteria entered his bloodstream and eventually shut down his organs. Jesse was taken to a nearby hospital for treatment and died a few days after that, his cousin said.

“In my mind, I was in complete disbelief,” she told WOFL. “I was like, ‘He’ll be fine. This could never happen to our family.’”

The Foundation for Orange County Public Schools has started a memorial fund for Jesse to help his family with hospital and funeral expenses. The foundation said Jesse had attended Lakemont Elementary since kindergarten and was member of the school’s safety patrol.

“Jesse was kind and compassionate, looked out for others, adventurous, and truly an amazing friend and classmate,” the foundation said in a statement. “He also knew how to make the most of fun times with friends outside and lived life to the fullest with his BMX and dirt bike racing.”