If you'll read the article, "Multiple 911 calls went out from Martinsville High School."
EMS was called. EMS came. The student made it to the hospital, and died there.
The article doesn't say whether or not anyone tried Heimlich on the student.
EMS is not permitted to declare some one dead. The kid was probably dead when the EMTs got to the school, they performed life saving techniques that had no positive results.