Riot police on Tuesday fired live bullets in the air and clashed with dozens of opposition supporters in Ethiopia's capital, Addis Ababa.
Doctors at Addis Ababa's Black Lion Hospital said those killed had died from bullet wounds suffered in the Mercato area of the city where police had battled angry mobs on the second day of planned opposition-led protests against the May 15 polls.
They added that at least 13 other people were being treated
for gunshot wounds.
Plainclothes security officers arrested Berhanu Nega, vice chairman of the main opposition Coalition for Unity and Democracy, on the streets of Ethiopia's capital, Addis Ababa, following the unrest.
Security officers struck him in the face with the butts of their rifles and pistols as they arrested him, opposition officials said.
His party's leader, Hailu Shawel, was also arrested at his home, according to a lawyer for the opposition party.
At least 43 people were wounded
in the riots on Tuesday
It was not clear what charges they may face, but Prime Minister Meles Zenawi has accused the opposition of treason and committing "serious" crimes in the run-up to the 15 May elections.
The government has threatened legal action against the Coalition for Unity and Democracy, or CUD.
Ethiopian Information Minister Berhan Hailu blamed the country's main opposition group, the CUD for instigating the violence.
"The CUD has called for these demonstrations," he said.
"It is not a hidden agenda. It is part of a plan to disrupt the peace and stability of this country. The incident today is a continuation of previous disruptions."
Berhan declined to comment on casualty figures.
"To blame us for this violence is madness. The trouble was incited by the government simply because people were supporting us by hooting their car horns, the measures that the police took ... were excessive," Gizachew said.
Opposition spokesman Gizachew Shiferaw urged supporters to stay calm and accused police of using excessive force.
"To blame us for this violence is madness. The trouble was incited by the government simply because people were supporting us by hooting their car horns, the measures that the police took ... were excessive"
Tuesday's violence took place a day after police arrested 30 taxi drivers and revoked their licences for taking part in renewed protests.
Protests against alleged electoral fraud in June saw police kill at least 42 people.
The riots began on the day the government threatened legal action against the main opposition Coalition for Unity and Democracy, or CUD.
The party has been boycotting Ethiopia's lower house of parliament, saying it wants a solution to the contested results of the May parliamentary election before taking up its seats.
Ethiopia's main opposition party
contests the May election results
The party has 109 seats in the 547-member Council of People's Representatives.
Opposition parties have claimed that hundreds of their supporters and members have been arrested in the past two months.
"Taking the CUD to court for its stance against the constitution is timely," the government said in a statement.
Riots subsided later on Tuesday after hundreds of riot police reinforcements were deployed.
Businesses, however, remained shut in Mercato as smoke billowed from tyres burning on the streets that were also littered with broken glass.