ADDIS ABABA - Demonstrators flooded the Ethiopian capital Addis Ababa on Monday, blocking roads and shutting businesses in an explosion of anger following the killing of 23 people on the city's outskirts over the weekend.

The unrest in Ethiopia's largest city was the latest instance of ethnic violence to challenge Prime Minister Abiy Ahmed, who has undertaken aggressive reforms including reigning in the security forces since his April inauguration.

Police appeared spread thin as groups of mostly young men waving protest flags and tree branches jogged through neighbourhoods across the city to denounce the weekend killings in the Burayu suburb. Ethiopia's police chief, Zeynu Jemal, said officers had shot dead five people on Monday, describing them as "dangerous vagrants" who attempted to loot property and steal police weapons. "I came for justice because our brothers and sisters are being slaughtered and thrown into the woods," said Bizuayehu Biyargegne Getahun, one of a group of more than a hundred protesters gathered in the central Meskel Square.

"They're raping our sisters and mothers," she claimed.

Zewdu Tinae called on the government to prevent the violence that he said had killed his brother and neighbour.

"The government is saying let's come together, but we're being driven apart because there's no rule of law," he said.

State-owned Ethiopia News Agency (ENA) said the violence in Burayu was carried out by an organised mob, who looted, killed and forced 886 people out of their homes, citing Alemayehu Ejigu, police commissioner for the Oromia region that surrounds Addis Ababa and includes Burayu.

Local media reported up to 200 arrests.

On Twitter, Abiy's chief of staff, Fitsum Arega, said the leader "strongly condemns the killings and acts of violence against innocent citizens.

"These cowardly attacks represent a grave concern to the unity and solidarity of our people and will be met with an appropriate response," he said.

But that wasn't enough for many protesters, who blamed the Oromos, Ethiopia's largest ethnicity which inhabits Oromia, for targeting minorities.

"People of Gamo and people of other ethnicities are being attacked," said Mahmud Emersa, referring to a minority ethnic group from southern Ethiopia.

He claimed the violence has gone on for the past four years.

The roads to Burayu were blocked by protesters on Monday, who threatened journalists covering the demonstrations.

Businesses closed their doors and avenues across the city were jammed with commuters waiting for public transportation that had greatly reduced due to the unrest.

There were no immediate reports of deaths or injuries in the demonstrations.

The weekend killings followed the triumphant return from exile of leaders of the once-outlawed Oromo Liberation Front (OLF) rebel group who in August agreed with Ethiopia's government to lay down arms.

But in the days before their return, clashes broke out between young men from the ethnically-mixed city of around four million people and Oromos who came into Addis Ababa to welcome the OLF.

Oromo-led anti-government protests that began in late 2015 helped bring about the resignation of Ethiopia's former leader and Abiy's subsequent rise to power.

An Oromo himself, Abiy has shuffled the leadership of Ethiopia's police, military and intelligence arms, which have long been accused of abusing human rights.

But while he's encouraged the people of Africa's second most-populous country to set aside their differences, bloody ethnic conflicts have rocked his administration.

The most serious began shortly after his inauguration, when clashes between Oromos and members of the Gedeo ethnic displaced nearly one million people.