(CBS News) CAMP BASTION, Afghanistan -- The Sept. 14 attack on Camp Bastion in Afghanistan's Helmand Province seemed to come from out of nowhere. A rocket-propelled grenade set the fuel storage tanks on fire, and the base turned into a battlefield.
The raid was the most costly enemy assault of the war in Afghanistan, killing two U.S. Marines and destroying six Marine attack jets -- aircraft which each cost between $20 million and $30 million.
Lt. Cmdr. Heather Tracy was off duty, reading, when it started.
"I could hear gunfire, multiple different loud noises," Tracy said. "I wasn't exactly sure where they were coming from or what direction initially."
Staff Sgt. Gustavo Delgado, a logistics specialist by day, grabbed his handgun and ran toward the sound of the fighting.
"I couldn't really see anything. We could just see shadows and smoke and as I started getting closer, that's when you could hear rounds whizzing by," Delgado said.
Fifteen insurgents were carrying rocket-propelled grenade launchers, assault rifles and suicide vests. They split into three teams, going after Harrier jets and attack helicopters.
Maj. Gen. Mark Gurganus, the top Marine commander on the base, knows how the insurgents managed to get through the base's defenses.
"I can tell you exactly how they got in. There's no mystery to it. There were no suicide bombers and there were no tunnels," Gurganus said.
According to Gurganus, the attackers used a simple pair of wire cutters to gain access to the base.
The Taliban released a video days later showing them practicing with wire cutters. Investigators say they had detailed knowledge of the layout of the base.
"There are guard towers ... we have more sophisticated guards in them, surveillance equipment, but it cant see everywhere all the time," Gurganus said.
Lt. Col. Christopher Raible, a fighter pilot and commanding officer, died defending the base, along with Sgt. Bradley Atwell, an aircraft technician.
The attack finally ended when pilots managed to get into helicopters in the middle of the gun fight, lift the aircraft off the ground and were guided to the insurgents by the Marines on the ground who were fighting them. They killed all of the attackers but one insurgent, who was wounded and is being held at the base.