One person was killed and more than 500 arrested as university students protested against Ethiopian election results they said were manipulated by the ruling party.
"A student was killed accidentally and seven seriously injured in a student riot today," Ethiopia's state-owned television quoted a police statement as saying.
The statement did not explain how the student died.
"A total of 520 university and high school students involved in the protests have been arrested and are in custody," it said.
The protest came despite a month-long ban on public demonstrations imposed by the government after the parliamentary election on May 15.
Tensions have been rising in Africa's top coffee grower since then, with the opposition accusing the ruling party of intimidation and vote rigging to stay in power.
"We shall struggle against the party which claims to have won the election when voters are declaring in clear terms they have not elected them," a leaflet passed out by the students said.
It accused the ruling party "of sowing the seeds of fear and suspicion among the Ethiopian people".
Police said the students had been incited by the opposition parties and were shouting slogans in support of the main opposition group, the Coalition for Unity and Democracy (CUD).
Police closed the doors at Addis Ababa University, the scene of deadly riots in 2001, before rounding up chanting protesters and taking them away in five police trucks.
Before the arrests, students behind the university's locked gates could be seen shouting, singing and chanting.
Witnesses had said that some of those detained had escaped after residents of a suburb in Addis Ababa blocked a road with rocks, allowing the students to jump out of the trucks and disappear into the bush.
Police fired in the air to stop others escaping, the witnesses said.
ABC News Online