They were four people charged with the safety of others, gunned down in a place where the nation's defense is the paramount mission for those who pass through its doors. They are being deemed heroes by some, and the cruel irony of protectors becoming targets was not lost, with President Barack Obama calling it "a heartbreaking circumstance" to lose four men who served "with great valor."
Here is a look at the Marines killed in the attack on two military facilities in Chattanooga, Tennessee:
Lance Cpl. Squire Wells, who was known as Skip, was swapping text messages Thursday with his girlfriend of 2 ½ years, excited that she had booked a flight to visit him in Chattanooga after months apart.
"Can't wait anymore," Wells texted. "Yes you can honey," his girlfriend, Caroline Dove, replied.
His next two words would be the last she'd ever hear from him.
"ACTIVE SHOOTER," he wrote.
She thought he was kidding: "You are so weird," she replied.
Hours of silence. "I love you," she tried. Hours more passed, the news out of Chattanooga becoming clearer. "Hon, I need you to answer me please," she wrote.
It would not be until Friday that she learned his fate.
The two met at Georgia Southern University, but he soon followed in his family footsteps and enlisted. His grandfather had been in the Air Force, and his grandmother and mother served in the Navy, Dove said.
Through tears, Dove remembered her boyfriend's love of flag football and Nerf guns, his passion for U.S. history, his ability to handle her when she was grouchy and how good he was at listening. He dreamed of being a drill sergeant, and when they last saw each other around Valentine's Day, he gave her a gold-and-silver ring. When the time came to propose, she said, he knew to ask her parents first.
Wells' mother was watching television coverage of the shooting when Marines appeared at her door. She knew what the visit meant.
"Every service parent, especially moms, dreads opening the front door and seeing people in uniform," said Andy Kingery, a friend who is acting as a family spokesman.
Ripples of grief were apparent as a stream of visitors brought flowers, food and gifts Friday to the Hampden, Massachusetts, home of Jerry and Betty Sullivan, the parents of Gunnery Sgt. Thomas Sullivan. A police officer was stationed outside to keep reporters and onlookers away. Masslive.com said Sullivan, 40, grew up in Springfield, Massachusetts.
The Pentagon said he had been enlisted nearly 18 years, serving two tours of duty in Iraq and earning two Purple Hearts.
His hometown mayor, Dominic Sarno, called Sullivan a man who "dedicated his life in brave service." Gov. Charlie Baker ordered flags to half-staff as he proclaimed "Terror comes home to Massachusetts." Sullivan's unit — India Battery, 3rd Battalion, 12th Marines — called him "one of our own" on its Facebook page. A giant U.S. flag and another representing the Marine Corps hung outside a Springfield restaurant owned by Sullivan's brother Joseph.
"He was our hero," read a post on the Facebook page of Nathan Bill's Bar and Restaurant, "and he will never be forgotten."
Outside the home of Sullivan's parents, Hampden Police Chief Jeff Fansworth told reporters the family was in shock and disbelief.
"How hard would it be for anybody to lose a child?" he asked. "It doesn't get much harder than that."
So proud a Marine was Sgt. Carson Holmquist that when he finished boot camp, he returned to his hometown of Grantsburg, Wisconsin, and paid a visit to his high school dressed in his formal blues. Grantsburg High School Principal Josh Watt, who was one of Holmquist's football coaches, remembers the day his former cornerback showed up, the pride in his accomplishment apparent.
"When he became a Marine he was very proud of that," Watt said Friday.
The principal remembered Holmquist as a strong player, an avid sportsman who loved to hunt and fish, a young man committed to succeeding. He graduated in 2008; the Pentagon said he enlisted in January 2009 and was serving as an automotive maintenance technician. He had completed two deployments as part of Operation Enduring Freedom.
Reached by phone, the slain Marine's father said he wasn't ready to talk yet, and his grandmother declined to comment as well. Sadness over the loss was permeating his small hometown.
"It's a very tough day in Grantsburg," Watt said.
Tony Ward remembered Staff Sgt. David Wyatt as the young Boy Scout who would run up mountains, just for fun, seeking to best the time of others.
Ward, who now lives in Helena, Montana, was Wyatt's scoutmaster when he was in high school in Russellville, Arkansas. Wyatt and Ward's son were good friends and worked together at a Boy Scout camp. He said Wyatt attained the Eagle Scout rank and graduated from high school in 1991. He was married with young children, Ward said.
Wyatt enlisted in 2004, the Pentagon said, and had been living in Burke County, North Carolina. He was deployed three times, including twice in Iraq.
Ward called the fallen Marine a man who enjoyed life, a "hard charger," someone who cared about his job and those who served with him.
"He's the kind of man that this country needs more of," he said.
Bynum reported from Savannah, Georgia. Associated Press writers Mark Pratt in Boston; Rodrique Ngowi in Hampden, Massachusetts; Ray Henry in Atlanta; Steve Karnowski in Minneapolis; and Kristin M. Hall in Nashville, Tennessee, contributed to this report.