ADDIS ABABA, Ethiopia (AP) — More than 80 people have been killed in unrest in Ethiopia after a popular singer was shot dead this week, the state-run Ethiopian Broadcasting Corporation says. Hachalu Hundessa was buried Thursday amid tight security.

He had been a prominent voice in anti-government protests that led to a change in leadership in 2018. Angry protests, including three bomb blasts, followed his death Monday in the capital, Addis Ababa. Scores of people were killed the next day, police in the Oromia region told the state broadcaster.

The unrest poses a major challenge for Prime Minister Abiy Ahmed, who took power in 2018 and introduced sweeping political reforms for which he was awarded the Nobel Peace Prize last year. The singer’s killing has further increased tensions after the government recently delayed the national election, citing the coronavirus pandemic.

Abiy on Thursday said the government will do whatever it takes to restore calm. He hinted there could be links to the killing of the army chief last year and the grenade thrown at one of his own rallies in 2018.

“Our enemies think they will create a conflict and dismantle the country,” he said. “However, this incident ... makes us unite together and stop them.”

Police late Wednesday said three people had been arrested in the death of the singer, who was buried in his hometown of Ambo. His service was carried on national television.

“Now I do not have anything to say. I only beg you, my son, to get justice,” his father, Hundessa Bonssaa, said.

The mood remained tense and fearful in Addis Ababa as some residents formed protection groups to defend their property from vandals. Hundreds of cars this week have been burned or damaged. Downtown streets were largely empty aside from fire trucks and ambulances.

Internet and mobile data service remain cut in Ethiopia as human rights groups raise concerns about the restrictions. The shutdown has “made it impossible to access information on those killed and injured in the protests,” Human Rights Watch said.

Other arrests this week include that of a well-known Oromo activist, Jawar Mohammed, and more than 30 supporters. The arrest of opposition figures “could make a volatile situation even worse,” Human Rights Watch said,

In the United States, members of the Oromo community protested the singer's killing Wednesday in St. Paul, Minn., stopping traffic on an interstate during the evening rush hour.

Ethiopia's prime minister has seen his administration’s sweeping reforms challenged as the loosening of political space opened the way for ethnic and other grievances, leading in some cases to deadly intercommunal violence.

Abiy earlier called the singer’s killing a “tragedy” and declared that “our enemies will not succeed.”