At least six people have been killed and several others wounded in a series of attacks in Burudian capital of Bujumbura on Sunday night, media reports said.

Three people were killed when armed gunmen opened fire overnight on Sunday evening, while three others were killed in two separate gun attacks across Bujumbura, according to Mail and Guardian.

"There have been several armed criminal attacks in many neighborhoods of Bujumbura which were apparently coordinated," a senior police officer said, according to AFP.

Armed assailants also attacked the residence of Bujumbura's mayor, Freddy Mbonimpa, on Sunday in the middle of the night. "Around 10 assailants ... shot and threw grenades at my house. We fortunately registered no death because my guard responded," Mbonimpa told Reuters.

Mbonimpa - a member of President Pierre Nkurunziza's CNDD FDD party - and his family were not hurt in the attack, according to World Weekly. Nkurunziza recently won a third term after a controversial election that was boycotted by main opposition groups

Last week, the United Nations Security Council (UNSC) adopted a resolution that warned mounting violence in Burundi could led to potentially "devastating consequences" for the entire region, as HNGN previously reported. The 15-member U.N. body also mulled the possibility of troop deployment in the east African country, while condemning the recent wave of violence and human rights violations in the country.

Nearly 250 people have been killed and tens of thousands have fled their homes due to violence that erupted after Nkurunziza decided to run for reelection.