A man accused of trying to seize control of Ethiopia’s northern Amhara state has been shot dead and a number of other plotters arrested, a senior government official has said.

Gen Asamnew Tsige was accused of masterminding gun attacks on Saturday night that killed five people, including the national army’s chief of staff and Amhara’s state president.

Asamnew was shot on Monday near Amhara’s capital, Bahir Dar, the prime minister’s press secretary, Negussu Tilahun, said. He declined to give any further details.

The reasons behind the attempted coup in the state remain unclear, although it may have been a reaction from Asamnew to a plan by state officials to rein him in after they were alarmed by reports of his ethnic rhetoric and recruitment of militias.

The violence on Saturday unfolded in two separate attacks. The army’s chief of staff, Seare Mekonnen, and a retired general were shot by Seare’s bodyguard at his residence in the national capital, Addis Ababa.

The Amhara state president, Ambachew Mekonnen, and an adviser were killed in Bahir Dar. Amhara’s attorney general was also shot, and died of his wounds on Monday, state media reported.

Access to the internet appeared to be blocked across Ethiopia, users reported. The streets of Addis Ababa appeared calm on Monday.

The Ethiopian prime minister, Abiy Ahmed, has pushed through sweeping changes since coming to power in April last year – making peace with Eritrea, reining in the security services, releasing political prisoners and lifting bans on some outlawed separatist groups.

The reforms in Africa’s second-most populous country have won him widespread international praise.

But the prime minister’s shakeup of the military and intelligence services has earned him powerful enemies at home, while his government has struggled to contain powerful figures in Ethiopia’s myriad ethnic groups fighting the federal government and each other for greater influence and resources.

The shooting in Bahir Dar at the weekend occurred when the state president – an ally of Abiy – was holding a meeting to decide how to stop Asamnew’s open recruitment of ethnic Amhara militias, one official told Reuters.

Asamnew had told the Amhara people to arm themselves and prepare for fighting against other groups in a video spread on Facebook a week earlier. Amhara is home to Ethiopia’s second largest ethnic group and gives its name to the state language, Amharic.

Asamnew himself was released from prison last year after receiving an amnesty for a similar coup attempt.

William Davison, an Ethiopia analyst at the global thinktank Crisis Group, said more information was needed on the attack on Seare.

“It doesn’t appear to have been a concerted national coup attempt. It’s not obvious what the motivations were for anyone to assassinate the chief of staff, or whether he had any connections to the violence in Bahir Dar,” he said. “More detail is needed on that aspect.”

Long-simmering ethnic tensions in Amhara and other areas has surged since Abiy’s reforms. At least 2.4 million people have fled the fighting, according to the UN.

Ethiopia will observe a day of national mourning on Monday, the parliamentary speaker, Tagesse Chafo, said on state television.

Ethiopia is due to hold parliamentary elections next year, although the electoral board warned earlier this month that the polls were behind schedule and that instability could cause a problem for voting.