(CNN)A University of Nevada Las Vegas student died just days after participating in a fraternity's charity boxing match where he collapsed soon after the fight, according to statements from the university and his family's attorney.
In what the school described as "a tragic incident," Nathan Tyler Valencia, 20, died Tuesday, four days after participating in Kappa Sigma fraternity's "Fight Night" on November 19.
According to an online flyer for the event, Valencia was one of the fighters participating in the card's "main event," but family attorney Nick Lasso told CNN Sunday that the junior kinesiology major had no boxing experience prior to taking part in the off-campus charity bout.
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Valencia collapsed "soon after his fight," according to an online letter to the campus community from UNLV President Keith Whitfield.
He was hospitalized following his collapse and died November 23, just four days shy of his 21st birthday, according to Lasso.
Valencia's official cause of death has not been released, however doctors determined he was suffering from internal bleeding at some point in his hospital stay, according to CNN affiliate KTNV.
"Kappa Sigma Fraternity is greatly saddened by the loss of Nathan Valencia at the University of Nevada, Las Vegas," fraternity executive director Mitchell B. Wilson said to CNN in an email Sunday. "Our deepest condolences, thoughts and prayers are with the Valencia family and the entire UNLV community."
Valencia was a member of UNLV's Sigma Alpha Epsilon fraternity and not the Kappa Sigma organization that hosted the event, according to Lasso.
According to an online flyer for the bout, the event was a fundraiser for Center Ring Boxing, a Las Vegas-based organization that establishes youth boxing programs for area children and their families.
In a statement to CNN, Lasso said his law firm will conduct "a full investigation" into the promotion, safety protocols, officiating and medical supervision of the November 19 event held in Valencia's hometown of Las Vegas.
The University of Nevada, Las Vegas campus.
KTNV said the Las Vegas Metropolitan Police Department opened an investigation into the incident. Police officials did not return a call from CNN Sunday night.
"The Valencia family is heartbroken over the loss of Nathan ... College students should not be placed in a situation where they are pitted against each other for combat," the statement from Lasso and Ryan Zimmer of the Richard Harris Law Firm reads. "The family wants to make sure this never happens again, that's the primary focus," Lasso told CNN by phone Sunday.
"We are shocked and heartbroken as we mourn the loss of one of our own," Whitfield said in his letter to the UNLV community. "Our deepest sympathies go out to his family, friends, and loved ones. I am sure words cannot describe their feeling of grief and emptiness," the school president added.
A vigil for Valencia was held on the UNLV campus Saturday night.
"He was the best person that anybody could ever ask for. I wouldn't wish this on anybody," Malcolm McGruder, Valencia's Sigma Alpha Epsilon fraternity brother told KTNV.