Attahiru had been appointed to the position earlier this year by President Muhammadu Buhari.
Nigeria's Chief of Army staff Lt. Gen. Ibrahim Attahiru and 10 other officers were killed Friday in a plane crash, the military said late Friday.
The military officials were en route to the capital, Abuja, after making an official trip to Kaduna state.
There was no immediate information provided about what may have caused the plane crash, but Brigadier Gen. Mohammed Yerima said more details would be released soon. The names of the other military officials who died were not made public.
The U.S. diplomatic mission to Nigeria called Attahiru's death “a tremendous loss to Nigeria” on Twitter, adding: "We join Nigerians in mourning the tragic loss of life from today’s plane crash.
Attahiru had been appointed to the position earlier this year by President Muhammadu Buhari. The presidency tweeted photos of Buhari being briefed by the country's defense minister and others about the crash.
“All of them are heroes who paid the ultimate price for peace and security in the land,” Buhari tweeted.