CBS News/ July 25, 2012, 3:30 PM

Staten Island high school football star dies after practice

Nick Dellaventura, 15, collapsed and died after a football exercise Monday, June 24, 2012. / WCBS

(CBS News) STATEN ISLAND - A talented high school athlete collapsed and died after football practice on a hot day with his teammates in Staten Island on Monday.

CBS New York reported that 15-year-old Nick Dellaventura had just finished practice drills with his team at St. Joseph by the Sea High School when he suddenly couldn't breathe or stand up on his own. He later died at the hospital.

"He was the best kid all around. Football-wise, he was the best on the field. He was the nicest kid in general," teammate Mike Motto told CBS 2's Hazel Sanchez.

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The cause of death is still unknown. One teammate said his face got "all blotchy" and "he said it would turn purple."

"Della was just trying his hardest and he just went down," Motto said.

The sophomore, described as powerhouse lineman, was the junior varsity team captain. He also played varsity last year.

The team had just taken part of a 90-minute conditioning practice that featured no equipment or physical contacts. The players said Dellaventura showed no signs of illness during the exercise.