At least two people died in overnight violence in Burundi's capital, Bujumbura, witnesses reported Sunday, as tensions rise in the lead-up to contested elections.
Burundi's opposition parties said they would not participate in national elections as a protest against the president's bid for a third term in office.
The opposition groups said they would boycott both parliamentary elections on Monday and a presidential vote on July 15, saying it would not be possible to hold a fair vote.
Meanwhile, parliament head Pie Ntavyohanyuma said he has fled to Belgium due to the violence, saying he fears for his life after opposing President Pierre Nkurunziza's decision to run for office.
Several top officials, including deputy vice-president Gervais Rufyikiri and members of the election commission and constitutional court, have also fled for the same reasons.
Critics of President Pierre Nkurunziza said he was violating the two-term limit in the constitution and the accords that ended Burundi's civil war. Burundi's constitutional court said the president was eligible to run again because he was elected by parliament, not voters, for his first five-year term in 2005.
Nkurunziza's bid for re-election triggered a failed coup attempt last month. The unrest has also forced more than 100,000 Burundians to flee to neighboring countries.
Burundi's United Nations ambassador, Albert Shingiro, said Friday that elections would go ahead as scheduled. He said another postponement would plunge the government into a constitutional vacuum. Shingiro told a U.N. Security Council meeting that 95 percent of the country wanted the vote and did not want to remain hostage to what he called a "radical minority which does not wish to see elections."
The United States said last week it would place on hold technical assistance to Burundi's electoral commission because of President Nkurunziza's planned to run for a third term.
U.S. State Department spokesman John Kirby said the United States supported the African Union's call for elections to be postponed until all parties could agree on a timetable and necessary conditions for a vote.
U.N. Secretary General Ban Ki-moon added his voice to growing calls for Burundi's election to be postponed in order to allow time for what he called "a conductive environment for inclusive, peaceful and transparent elections."
On Thursday, at least 100 students broke into the grounds of the U.S. Embassy in Burundi to seek refuge from political violence.
Student protesters seeking refuge crawl under the gates of the U.S. Embassy in the capital Bujumbura, Burundi, June 25, 2015.
The U.S. Embassy said the students remained peacefully in the embassy parking lot. They had been camping outside the embassy compound for weeks after the government closed their university in April.
Several people have been wounded in grenade blasts in Bujumbura recently, following the president's announcement.
Burundi's second vice president, Gervais Rufyikiri, has fled the country and denounced President Nkurunziza's bid to extend his stay in power.
The second vice president is believed to be in Belgium. The president's office told VOA that Rufyikiri went there on a mission a few days ago.
VOA reporter Edward Rwena, who is in Burundi's capital, said the country's first vice president, Prosper Bazombanza, remained in the country.
Some information for this report came from AP, AFP and Reuters.