The blast happened at the first rally that Prime Minister Abiy Ahmed had called in the capital Addis Ababa. It was not immediately known who was behind the attack, but police have reportedly arrested six people in connection with the attack.
Ethiopia's new Prime Minister Abiy Ahmed escaped a grenade attack on Saturday at a rally in the capital that killed two people and left scores wounded, officials and witnesses said.
The attack was launched by an unidentified assailant moments after 41-year-old prime minister, a former soldier who took office in April, finished his speech to tens of thousands of people gathered in the centre of Addis Ababa.
A witness saw Abiy whisked away by guards. Another witness told Reuters the assailant with the grenade had been wrestled to the ground by police before it exploded.
The State-run Ethiopian News Agency reported on Sunday that police had arrested six people suspected of involvement in the blast, but gave few details.
No group has publicly claimed responsibility for the attack.
Health Minister Amir Aman had earlier said one person had been killed and 154 were wounded, of which 10 were in critical condition.
However, another person succumbed to their wounds on Sunday.
"I’m so sorry to learn that we have lost another Ethiopian victim of yesterday’s attack who was in ICU at Black Lion Hospital," Health Minister Amir Aman said on Twitter on Sunday. "My sincere sympathy and condolences to the family, friends & all Ethiopians."
TRT World's Reagan Des Vignes reports.
Abiy had just wrapped up his speech in the heart of Addis Ababa when the explosion went off, sending panicked crowds towards the stage as the prime minister left hurriedly, an AFP correspondent said.
Abiy said the blast was orchestrated by groups who wanted to undermine the rally, without elaborating, according to state-affiliated Fana Broadcasting Corporate.
"All the casualties are martyrs of love and peace," Abiy was quoted as saying.
In a televised addressed after the explosion, Abiy described the incident as "an unsuccessful attempt by forces who do not want to see Ethiopia united."
Police fired tear gas as they moved in to clear Meskel square where the rally was held, the AFP correspondent said.
It was Abiy's first public speech in the capital since he took office in April, although he has made several in provincial areas.
In the past three months, Abiy has made major changes in Ethiopia including shaking up the security services, releasing jailed dissidents, moving to liberalise the economy and to resolve a two-decade conflict with arch-enemy Eritrea.
"Ethiopia will be on top again, and the foundations will be love, unity and inclusivity," he declared on Saturday, dressed in a green T-shirt and a hat.
After the blast, dozens of people stormed the stage, hurling various objects at police, shouting, "Woyane down, down," and "Woyane thief", using a pejorative term for the government, the AFP correspondent said.
Abiy succeeded Hailemariam Desalegn, who resigned in February amid a wave of anti-government protests led by the country's two largest ethnicities, that started in late 2015 and left hundreds of people dead.
His actions since coming to power represent dramatic shifts in the power balance within Africa's second-most populous country.
But it remains unclear how deep Abiy's support runs within the ruling Ethiopian People's Revolutionary Democratic Front (EPRDF) for carrying out the reforms.
On Friday, Ethiopian opposition group Ginbot 7 announced it would cease armed attacks in the country following the reforms announced by the new government.
Last month, Ethiopia released from prison top Ginbot 7 official Andargachew Tsige.
Prosecutors also dropped charges against the group's leader Berhanu Nega, who is based outside Ethiopia and had in 2009 received a death sentence in absentia over an assassination plot.
"Our forces have received strict orders to refrain from any sort of armed resistance," the group said in a statement.
Formed after a disputed 2005 election, Ginbot 7 – named after the date in the Ethiopian calendar when the ballot took place – has claimed numerous deadly attacks in the past.
Senior police official arrested over security shortcomings
The deputy commissioner of the Addis Ababa Police Commission has been arrested and is being investigated for shortcomings in security after a grenade attack in the Ethiopian capital killed one person and left scores wounded, according to state-run TV.
"Nine individuals, including the Deputy Commissioner of the Addis Ababa Police Commission, are in custody and under investigation over shortcomings" in security, the Ethiopian Broadcasting Corporation said on Saturday.