A graduate of Staples High School in Westport was among the seven Marines killed during a training exercise at Hawthorne Army Depot in Nevada.
Roger Muchnick, 23, had been in the Marines for about three years and served in Afghanistan.
He played high school lacrosse and football in Westport and later played lacrosse at Eastern Connecticut State University, where he studied business.
In a biography on the university's website, Muchnick said the one thing he would like to do before he died was "live," and his most embarrassing moment was getting caught lip-synching in a school talent show.
"He was at the top of his game when this happened," said his grandfather, Jerome Muchnick. "You can't imagine losing a very handsome, 23-year-old grandson who was vital and loving."
The mortar shell explosion Monday night involved the 2nd Marine Expeditionary Force from Camp Lejeune. Seven men were killed and eight were injured, officials said. A Navy corpsman is among the injured.
“This is a sad day for Westport where Roger grew up. At Staples, he was well known as a popular football and lacrosse player and was well-liked by his friends, teachers and coaches," Westport First Selectman Gordon Joseloff said in a statement.