A rising football star at a Staten Island high school died this week after collapsing on the field.

As CBS 2's Weijia Jiang reported, Curtis High School student Miles Kirkland-Thomas, 16, collapsed during practice Monday morning. It was one of the hottest, most humid days of the year.

Teammate Amad Anderson said they ran up the field a dozen times then took a water break. The players were doing individual workouts when Kirkland-Thomas passed out.

"We don't know what happened, but he just fell," Anderson told 1010 WINS' Glenn Schuck. "I think he was overheated, probably, but he just, he fell."

Kirkland-Thomas was in cardiac arrest when an ambulance rushed him to the hospital, where he was pronounced dead.

At his home in the West Brighton houses, Kirkland-Thomas's grandmother, Florence McNatt, is still stunned that he died.

"His mama has been up all night crying," McNatt told CBS 2's Jiang. "We are all crying."

"I'm very, very upset and I know he's in heaven now," his 8-year-old cousin Blake McNatt said.

At nearby Curtis High School, the boy's friends brought candles and messages to the fence of the field where the 16-year-old practiced and played as number 54 on the school's football team.

"It's such a tragedy because the school year just started and we all miss him," friend Sashoia Williams said.

Relatives and family friends say they did not know of any underlying medical conditions that would explain the boy's death, CBS 2's Dave Carlin reported.

"They shouldn't push that hard. He showed up late but he did show up, they should not make him do sprint," Williams said.

Kirkland-Thomas was a leader at home and on the team. He had big plans to earn a football scholarship to go to college.

"He was a good kid, he was a hardworking kid, he loved football," Anderson told WCBS 880's Sean Adams. "The whole football team loved him, all the parents on the football team loved him. He always looked out for your kid."

At the housing development where he lived, Kirkland-Thomas was a role model who viewed football as more than a hobby. Loved ones said it was his ticket to escaping a life of poverty.

"Living in the projects, you see kids doing different things," said family friend Anthony Royal. "This kid was into football, church. There's not too many kids like that, you know? And it's heartbreaking. It's tragic."

The teen was a 6-foot-2, 320-pound defensive lineman. His father, Jamar Thomas, told the New York Daily News his son had passed a physical in July and the family was not aware of any pre-existing conditions.

An autopsy will determine the cause of death and if heat was a factor.