Police on Monday fired tear gas and water cannon at protesters rallying in Burundi's capital to oppose President Pierre Nkurunziza's plan to run for a third term, a move they saw as a violation of the peace deal that ended a civil war 10 years ago.
Nkurunziza's spokesman called the protests an "insurrection" and said the opposition was trying to take Burundi back to 1993, when the war broke out.
"The fight continues," people chanted as crowds gathered in in several parts of Bujumbura for a second day of protests.
The protesters blocked roads with burning tyres and large stones. A Reuters reporter said the army had been deployed on the streets.
Nkurunziza's announcement on Saturday that he would run in a June 26 election triggered the unrest. Activists say he is breaking the constitution and the Arusha peace agreement that ended the war, both documents which limit the president to two five-year terms.
His supporters say his first term does not count as he was picked by lawmakers, not elected.
Both sides accused each other of stoking ethnic tensions similar to those that lead to the war.
"These people, they want to bring us back to those years where this country suffered very bad ethnic divisions, ethnically-motivated killings and assassinations," Nkurunziza's spokesman Gervais Abayeho said.
The civil war pitted the army, then dominated by the ethnic Tutsi minority, against rebel groups mostly made up of majority Hutus, one of them led by Nkurunziza. The army now includes both ethnic groups.
The prospect of a build-up of ethnic tensions in Burundi will sound alarm bells across a region still scarred by the 1994 genocide in Rwanda, where more than 800,000 mostly Tutsis and moderate Hutus were killed.
Rwandan officials said more than 20,000 people had now fled from Burundi to Rwanda. Thousands have also fled to neighbouring Democratic Republic of Congo.
Police also moved against radio stations on Monday.
They raided and shut down the Radio Broadcasters' Association studio and closed private radio station RPA for broadcasting live on the protests. Abayeho said RPA was fuelling violence.
RPA director Bob Rugurika said his station and two others had already been stopped from broadcasting in the countryside, where much of Nkurunziza's popular support is based.
Police slapped and kicked prominent activist Pierre Claver Mbonimpa as they arrested him after he appeared on a live radio programme, a Reuters reporter said.
FIVE DEATHS ON SUNDAY
The presidency said three people had been killed and 15 police officers were hurt during clashes in Bujumbura on Sunday.
Hours before his arrest, Mbonimpa told Reuters at least five people were killed on Sunday, three of them in protests and two more in an attack by the ruling party's Imbonerakure youth wing.
"The military are aware that we are going to hold protests, but have warned us that they should remain peaceful and that’s all we are asking for," Mbonimpa said.
The police had no comment on any casualties.
The ruling CNDD-FDD party has repeatedly denied charges its youth wing is armed and trying to cause violence.
Diplomats and opponents say the police are seen as more aligned to the ruling party, a charge the party denies.
African and Western nations had all pressed Nkurunziza not to run again. The U.S. State Department said it was disappointed by the president's decision.