Seth Martin, a 15-year-old student at Cement High School, collapsed Tuesday during a game against Union City, the Oklahoman reported.
He died later after being transported to Oklahoma University Medical Center.
Martin was diagnosed with Vocal Cord Dysfunction, a condition where a person's vocal cords close instead of open when breathing in and out, which has caused some issues with playing basketball for the teen.
However, Martin's older brother, Zachary Wright, said doctors believe Martin's death was caused by his heart.
"He loved basketball," Wright said. "He wasn't going to let that stop him from playing."
"Everybody's in shock," Cement superintendent Danny Pittman said. "Fortunately, we've been pretty lucky that we have several counselors from around the area and we also have several of our local ministers here today. We're making plans for the next several days in trying to make sure we're taking care of our staff and our students."