Finn was the oldest of 97 Medal of Honor recipients from World War II still living. He died at a nursing home for veterans in Chula Vista, outside San Diego, according to a Navy statement.
Despite head wounds and other injuries, Finn, the chief of ordnance for an air squadron, continuously fired a .50-caliber machine gun from an exposed position as bullets and bombs pounded the Naval Air Station at Kaneohe Bay on Oahu. He then supervised the rearming of returning American planes.
"Here they're paying you for doing your duty, and that's what I did," Finn told The Associated Press before his 100th birthday. "I never intended to be a hero. But on Dec. 7, by God, we're in a war."
President Obama said "his modesty does not diminish his extraordinary conduct or the incredible example he has set for our men and women in uniform and for all Americans."
"I had the privilege of meeting Lt. Finn last year, and I was struck by his warmth and humility," Obama said in a statement from the White House.
Finn, who enlisted in the Navy just before his 17th birthday, received the Medal of Honor on Sept. 15, 1942.
He later served as a limited-duty officer specializing in anti-aircraft guns in San Diego, Hawaii, Washington, Panama and aboard aircraft carriers, the Navy said.
Finn retired in 1956 after three decades of service, but he continued to help young Sailors and stayed active in Navy organizations, Lt. Aaron Kakiel said.
He will be buried with full military honors.
God's Speed John - Rest in Peace
