Fatal H.S. Track Meet Stabbing Stemmed From Seat Dispute, Victim's Brother Says

The brother of the 17-year-old high school athlete who was stabbed to death at a track meet on Wednesday said the tragic incident was all sparked by an argument over a seat.

Hunter Metcalf told WFAA his twin brother, Austin Metcalf, got into a tiff with Karmelo Anthony while out at the event in Texas ... because the Frisco Centennial High School 17-year-old was sitting underneath their Frisco Memorial High School tent.

"We asked him to move," Hunter said. "He started getting aggressive and talking reckless."

"And my brother stepped in and said, 'You need to move.' And he's like, 'Make me move.' All the sudden, he grabbed his backpack."

Hunter said just seconds later, he saw his brother suffering from a stab wound.

Authorities said first responders got to Metcalf at around 10 AM, but despite administering lifesaving efforts, he passed away.

Anthony was arrested and charged with one first-degree felony count of murder ... and as of Wednesday evening, he was being held with no bond.

Hunter said neither he nor his twin had ever encountered the teen before Wednesday's incident.

"It really was under 30 seconds, this altercation," he said. "I never met this kid in my life."

A GoFundMe campaign has been launched by the Metcalfs' father, Jeff ... and over $84K had been raised as of Thursday morning.

"His passion for football was unbelievable," Jeff said. "Voted team MVP this past season and carried a 4.0 GPA."