Gunnery Sgt. Thomas Sullivan got 13 Marines and a sailor over the green fence in the back corner of the compound as his unit rushed to escape a gunman's bullets on the morning of July 16.
The Marines hoisted each other up the fence and Sgt. Jeff Cantu, supply chief, was one of the last men over.
"Once I got over the fence, I turned around and Gunny was gone," he said. "I can't speak for what was going through his mind, but I immediately thought, 'I don't know where he's at,' and 'He went back in.'"
Sullivan, 40, would die in the attack that had started moments earlier, when Mohammad Youssef Abdulazeez, 24, stormed the U.S. Naval and Marine Reserve Center on Amnicola Highway around 11 a.m. July 16. Abdulazeez killed four Marines and a Navy specialist before he was killed by police.
The shooter used a rented Mustang to smash through the front gate of the complex, according to the FBI, then jumped out of the car and attacked the reserve center armed with an assault rifle, handgun and ammunition. As Abdulazeez approached, an unidentified service member inside fired at him.
Abdulazeez responded by firing back. He made it inside the door and mortally wounded U.S. Navy Petty Officer 2nd Class Randall Smith, 26.
Cantu was inside the same building when he heard the first shot.
Initially, he thought the Marines working to count equipment in the warehouse out back had dropped something. But then the shooting intensified. He heard multiple "double taps" — two shots in quick succession — and the shots kept coming faster.
"We knew it was a shooter," he said. "And we knew where he was, basically. We started pushing out the back."
They could have made a quick exit out a side door, but instead the Marines continued out the back, aiming for the warehouse where they knew other Marines were working.
"It wasn't 'I need to be safe,' it was 'They need to be safe, we need to move out as a team,'" Cantu said.
Staff Sgt. Christopher "Chase" Estep was working in his office — closer to the shooter than Cantu — when a Marine burst in with the warning. Active shooter.
Estep, the Marine and a Navy corpsman slammed the door shut. Estep and the Marine climbed under his desk, while the corpsman stood with his back against the door, bracing his arms against the desk and the wall.
He'd keep it shut if Abdulazeez tried to come through.
Estep called 911 immediately, and stayed on the line with the dispatcher.
"I was trying to tell her where I could hear bullets and shots fired," he said.
Out back in the warehouse, Pfc. Aaron Noyes, supply clerk, was counting equipment with Lance Cpl. Skip Wells when someone rushed in with word of the active shooter. At first, Noyes thought it was a drill.
But he quickly realized it was real.
"We rushed out, and that is the last time I saw Lance Cpl. Wells, racing off toward the motorpool to make sure the guys back there knew what was going on," Noyes said.
Wells, 21, died in the attack.
Noyes and others met up with Sullivan and Cantu in the back, within the fenced compound. They started going over the fence. At one point, Cantu said, Sullivan ordered the group to move to another location where there was better cover and concealment. That's where it all culminated, Cantu said.
"He told us jump the fence, get to safety, get away from this," Noyes said.
Cantu went over. Sullivan stayed.
"I can't say for sure, but I know that he wanted to get us over that fence, and I don't think he had any intention of joining us over there," Cantu said of Sullivan.
Once they landed on the far side of the fence, Cantu, Noyes and the group ran through the Tennessee Riverpark, yanking civilians away from the shooter. Noyes scooped up a small boy and carried him through the playground.
"When I saw the kids, all I could think about was my little brother," he said. "And I just did what I thought was right."
The group — 13 Marines and a sailor — took shelter at a maintenance complex in the park, keeping civilians inside. They took up posts and warned approaching citizens to get out of the area.
One such civilian was Ooltewah resident Paul Wagner, who was riding his bike south on the Riverwalk when three Marines came running down. They wore camouflage uniforms. They told him to turn around. There's an active shooter, they said.
He turned back toward the Chickamauga Dam and heard what sounded like gunshots as he rode. But he figured the event was just a drill, and stopped to wait on a bench. He tried to ride back through again a few minutes later and was turned away, again.
As details of the shooting emerged, he became more grateful for the Marines who kept him from danger.
"The fact that they had enough presence and clarity of mind to think about others who could wander into harm's way, to me, is just a tribute," he said.
In the maintenance complex, the Marines took a count, figured out who was there. Cantu called his first sergeant and reported who was in the park.
Then they waited for the all clear.
They didn't know that Sullivan, Wells, Staff Sgt. David Wyatt, 35, and Sgt. Carson Holmquist, 25, had already fallen.
"Of course we wondered," Cantu said. "That's the only thing the Marines talked about. 'Well, where's Wells? Where's Holmquist? Where are these guys?'
"All we could really say was, 'We don't know yet, we're split up. We don't know yet.'"
Contact staff writer Shelly Bradbury at 423-757-6525 or firstname.lastname@example.org with tips or story ideas.