An Army National Guard spokesman said the two soldiers were on a routine nighttime training mission when the helicopter went down near Pleasant Valley Road and Hollilynn Drive at about 7 p.m. Thursday.
The Idaho National Guard released the identities of the soldiers as chief warrant officers Stien P. Gearhart, 50, of Meridian, and Jon L. Hartway, 43, of Kuna.
"It's a very difficult evening for us in the Idaho National Guard," said Col. Tim Marsano, Idaho National Guard spokesman. "We don't know the reasons why -- we can't speculate at this point."
Both soldiers were assigned to 1-183rd Attack Reconnaissance Battalion.
"The men and women of the Idaho National Guard are united in grief at the loss of two of our brothers in arms, who gave their lives while training to defend our nation," said Idaho National Guard Commander, Major General Gary Sayler. "Today, our thoughts and prayers are with their families."
The helicopter sent out a beacon when it went down, Marsano said. It's one of 16 helicopters at the base.
According to the Ada County Coroner's office, there was no fire or explosion at the scene and the two soldiers' bodies were not burnt. He said debris was spread over the area. He noted they had been pilots for years.
Trina Holton, who lives on Pleasant Valley, said she heard just a loud rumble and a big band.
"I thought it was a prison break or something," Holton said. "it was very sad. I was hoping that they made it."
Chief warrant officer Hartman, from Kuna, was also a pilot for Air St. Lukes, according to Idaho Helicopters Director of Operations Steve Sandmeyer.
Idaho Helicopters works with Air St. Lukes, and also shares several pilots with the Idaho Army National Guard.
"The training that the pilots receive is outstanding," Sandmeyer said. "The quality of the maintenance service they have is also outstanding. It's the highest level."
Sandmeyer, who only knew Hartway on a professional level, said that his service for Air St. Lukes speaks volumes about his character, and only magnifies the loss.
"He's flown hundreds of people," he said. "If all you're able to do is impact one person's life in your life, how do you put a value on that? That kind of job is a very demanding job."
"Those calls come at all times of days and nights, and it needs the type of person who has the ability to stay very alert and very professional at all times," he said. "We're all very anxious as aviation professionals to find out what happened."
Gov. Butch Otter: "The First Lady and I mourn the loss of these Idaho Army National Guard pilots. Their loved ones and brothers and sisters in arms are in our thoughts and prayers."
"This tragedy reminds us of the enormous sacrifice and great risk involved in military service - whether here at home preparing to go into harm's way or on the battle lines of freedom. I ask all Idahoans to join me in honoring these courageous citizen soldiers along with all those who have gone before them in defense of the liberties we hold so dear."
Congressman Raul Labrador: "Rebecca and I send our thoughts and prayers to the families of the two Idaho National Guard pilots who died in the line of duty. Their sacrifice is a sober reminder of the price of freedom. We also are praying for the entire Idaho Guard community and ask that every Idahoan take special note of Veterans Day on Tuesday."
U.S. Senator Mike Crapo: "I am deeply saddened to learn of the passing of our Idaho National Guardsmen. My thoughts and prayers are with their families, friends and the entire Idaho National Guard community during this difficult time."
"This tragic event serves as a poignant reminder of the dedicated service and ongoing sacrifices our military men and women make to safeguard our freedoms."
U.S. Senator Jim Risch: "Vicki and I send our thoughts and prayers to the families of those lost. Because of my special relationship with the Idaho National Guard this hits all the harder."
"This once again reminds us of the dangers our dedicated servicemen and women face, at home and abroad, as they work hard to keep America safe."
Boise Mayor Dave Bieter: "I am deeply saddened by the tragic loss of the Idaho National Guard Pilots. Our thoughts and prayers are with the families of these brave men, along with their fellow soldiers of the Idaho National Guard. I ask our community to remember and honor these men as we all celebrate Veterans Day over the next several days."