Ethiopian musician Hachalu Hundessa, known for his political songs, was shot dead in the capital.
The 34-year-old man said he had received death threats and the police are now detaining several suspects.
Hachalu’s lyrics often focused on the country’s Oromo ethnic rights and became hymns in a wave of protests that led to the fall of the previous prime minister.
Demonstrations broke out in response to news of the musician’s death.
Shots were heard in Addis Ababa and people set tires on fire.
Thousands of fans went to the hospital in the city where the singer’s body was taken on Monday night, according to BBC Afaan Oromo’s Bekele Atoma.
For them, he was a voice of his generation that protested decades of government repression, he says.
The police used tear gas to disperse the crowd.
The internet was also closed in some parts of the country, when protests spread in the regional state of Oromia.
Hachalu’s body has now been taken to the city of Ambo, about 100 km west of the capital.
Prime Minister Abiy Ahmed expressed his condolences saying in a tweet that Ethiopia “lost a precious life today” and described the singer as “wonderful”.
What were Oromo’s protests about?
Oromo, Ethiopia’s largest ethnic group, has long complained of political and economic marginalization.
Demonstrations broke out in 2016 and pressure on the government.
The governing coalition ended up replacing then Prime Minister Hailemariam Desalegn with Abiy, who is Oromo himself.
It brought a series of reforms that transformed what was considered a very oppressive state.
He won the Nobel Peace Prize in 2019, mainly for making peace with ancient Eritrea, but his efforts to transform Ethiopia have also been recognized.