A Mississippi high school football player died on Monday, three days after falling ill during a game, school officials said.
Walker Wilbanks was playing in a Friday night game for Jackson Preparatory School, a private school in a suburb of Jackson, when he came off the field and complained that he was not feeling well, a school spokeswoman said.
Wilbanks was taken to a hospital where he suffered a seizure and swelling in his brain before he died, school spokeswoman Crisler Boone said.
A 17-year-old junior, Wilbanks was popular among his fellow students, Boone said.
"Everybody felt they were Walker's best friend because that's just the kind of guy he was," Boone said.
The cause of Wilbanks' death is not yet known, Boone said, referring medical questions to the University of Mississippi Medical Center.
Marc Rolph, a spokesman for the hospital, did not immediately return a message seeking comment.
A 2013 study published in the American Journal of Sports Medicine found that an average of 12 high school and college football players die annually during practices and games, with heart conditions, heat and other non-traumatic causes of death twice as common as injury-related ones.