General Seare Mekonnen is one of at least four senior officials to have been killed - as the government foiled a military take-over, in the region outside the capital, Addis Ababa.
Ethiopia's Prime Minister, Abiy Ahmed, told the state broadcaster that the attempt was orchestrated by Amhara state's security head, General Asamnew Tsige.
Amhara state president Ambachew Mekonnen and his adviser were also killed, according to state media.
A week ago, General Asamnew had openly advised the Amhara people, one of Ethiopia's larger ethnic groups, to arm themselves, in a video spread on Facebook and seen by a Reuters reporter.
Since being elected in April, Mr Abiy has had to grapple with increased ethnic violence in many places, including Amhara.
Attempting to spearhead political reforms amid widespread unrest, his government has released political prisoners, removed bans on political parties and prosecuted officials accused of gross human rights abuses.
Report from IRN.