General Seare Mekonnen died after being shot while trying to prevent the coup attempt on Saturday night, in which another military chief, General Gezai Abera, also died, the office said on state television ETV.
The president of Amhara region, Ambachew Mekonnen, as well as his adviser, Ezez Wasie, were also shot dead in their office in the regional capital, reports Efe news.
The coup against the government of this region, the second largest ethnic group in the country, began late Saturday in the capital, Bahir Dar, and was thwarted soon after by the federal security forces, the prime minister's spokesman, Nigussu Tilahun, announced on ETV.
"The coup attempt in Amhara regional state is against the constitution and is intended to scupper the hard-won peace of the region," the prime minister's office said in an initial statement.
"This illegal attempt should be condemned by all Ethiop and the federal government has full capacity to overpower this armed group," it added, without specifying who was behind the attempt.
In addition to Bahir Dar, shots were also heard in the country's capital, Addis Ababa, according to reports from the United States embassy in Ethiopia.
"The US Embassy is aware of reports of gunfire in Addis Ababa. Chief of Mission personnel are advised to shelter in place," it said in a statement.
Since coming to power in April 2018, ending two years of protests against the previous government, Ethiopian President Abiy Ahmed has been praised both within the country and outside it for his democratic advances, which have led to the return of exiled dissidents as well as the arrest of dozens of senior military and intelligence officials.
On July 9, 2018, Abiy and Eritrean President Isaias Afwerki signed a joint declaration of peace and friendship to pave the way for a thaw in diplomatic relations between the two countries, which had been suspended since the end of an armed conflict that began over border disputes dating back to the independence of Eritrea in 1993.
However, these same reforms and a more balanced distribution of power between the country's nine autonomous regions have also led to increased tensions between the various ethnic groups, with several spirals of violence in a nation of more than 100 million people.
Ethiopia, which has more than 80 different ethnic groups, had the largest newly displaced population in the world in 2018, more than two million, owing to intercommunal violence.
( With inputs from IANS )