The four Marines who were killed when a gunman opened fire at two military installations in Chattanooga on Thursday have been identified.

The victims were listed as 27-year-old Carson Holmquist, of Flintsone, Georgia; 40-year-old Thomas Sullivan, of Springfield, Massachusetts; 21-year old Skip Wells, of Marietta, Georgia; and 37-year old David Wyatt, of Hixon, Tennessee, WRBC detailed.

The gunman, 24-year-old Muhammed Youseef Abdulazeez, also died in the incident. Three more individuals, including a police officer, were injured in the shooting, according to the NBC affiliate.

President Barack Obama has said that the four Marines served "with great valor" and called their deaths a "heartbreaking circumstance," the Associated Press noted.

Holmquist had enlisted in January 2009 and had completed two foreign deployments as part of Operation Enduring Freedom. A sergeant with close ties to the local community in his hometown of Grantsburg, Wisconsin, he had returned to his high school upon finishing boot camp, Principal Josh Watt recalled.

"When he became a Marine he was very proud of that," Watt said on Friday as he remembered the former student as a strong player and avid sportsman who loved to hunt and fish.

Squire Wells, a lance corporal, enlisted in February 2014 and served as a field artillery cannoneer, the AP noted. His mother learned of the Marine's death as she received visitors while watching coverage of the Chattanooga shooting.

"Every service parent, especially moms, dreads opening the front door and seeing people in uniform," Andy Kingery, a friend who is acting as a family spokesman, told the newswire. "Skip Wells died doing what he wanted to do and had chosen to do," he added.

Sullivan, meanwhile, had been enlisted nearly 18 years and had served two tours of duty in Iraq. The gunnery sergeant was the recipient of two Purple Hearts, the medal awarded to members of the armed forces who are wounded in action.

"He was our hero," read a post on the Facebook page of Nathan Bill's Bar, a restaurant in his hometown of Hampden, Massachusetts. "He will never be forgotten," the message assured.