Protesters announced a two-day truce, but warned they would return to the streets on Monday unless President Pierre Nkurunziza backs down.
The United Nations voiced alarm over the central African nation's political crisis, saying the Nkurunziza's government was engaged in a brutal crackdown but "will not succeed in quashing dissent".
Social media has been blocked and radio stations have been shut down.
Sporadic clashes continued in parts of the capital Bujumbura today, witnesses said, while hundreds of university students -- whose student lodgings have been closed by the government -- have been camping outside the US embassy, saying they want protection.
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Police spokesman Pierre Nkurikiye told AFP that 577 arrests have been made, with nearly 250 cases sent for prosecution and 150 undergoing questioning. The remainder have been released.
A spokeswoman for the prosecutor's office, Agnes Bangiricenge, said those charged would be tried for "taking part in an uprising" and risked between five years and life behind bars.
A civil society leader today called on protesters to stop demonstrating for two days and urged the president to "take advantage of these 48 hours to think about the consequences of his project and to give up by Monday".
Activists would meanwhile give the protesters killed in six days of clashes "dignified burials", Nininahazwe told reporters.
The unrest broke out after the ruling CNDD-FDD party designated Nkurunziza as its candidate in the next presidential election, which is due to be held on June 26.
Opposition figures and rights groups say that Nkurunziza's attempt to stand for a third consecutive term violates the constitution as well as a peace deal that ended a civil war in 2006.