Burundi police blasted protesters with tear gas and water cannons Friday as hundreds demonstrated against President Pierre Nkurunziza running for a third term, in defiance of the constitution's two-term limit. “We won’t let him run again,” protesters in the capital Bujumbura shouted, Reuters said.

The tensions have caused more than 8,000 Burundians to flee to neighboring Rwanda and the Democratic Republic of Congo in the last two weeks, the United Nations refugee agency said Friday. More than 60 percent of the Burundians who went to Rwanda were children, and the number of refugees could increase “with more political tension rising and more acts of violence being reported,” UNHCR spokesman Adrian Edwards told Agence France-Presse in Geneva.

"In all, more than 8,000 Burundians have sought refuge in these two countries in the past two weeks, 7,099 in Rwanda and a smaller number in the Democratic Republic of Congo," Edwards said Friday. 

The United Nations said there were reports on the ground of opposition supporters mysteriously disappearing, AFP said. A report by Human Rights Watch found the Burundi government harassed opposition parties, activists and journalists. Members of the youth wing of the ruling party, National Council for the Defense of Democracy-Forces for the Defense of Democracy (CNDD-FDD), also committed violence against opponents, the human rights group in Washington said in January.

Burundi is scheduled to hold its general elections beginning next month. Voters will elect lawmakers in May and a president in June, but the latter is the most controversial poll for Burundians. Nkurunziza took office in 2005 as Burundi emerged from 12 years of civil war. The Burundian constitution and the peace deal that ended the war both state no president can serve for longer than 10 years. Nkurunziza’s supporters argue his first term should not count because he was selected by lawmakers rather than elected by voters, Reuters reported.

"The police used brutality to disperse peaceful protesters, but this will not discourage us. We will continue the struggle," Chauvineau Mugwingizo, a spokesman for the five opposition groups that called the protest, told Reuters Friday.