At least seven people including a police officer were killed overnight in separate incidents in Burundi’s capital and the surrounding area, police, witnesses and an official said on Wednesday.

The deaths are the latest in a wave of violence convulsing Burundi that has alarmed world powers, which fear the African nation may be sliding back into ethnic conflict after emerging in 2005 from a 12-year civil war.

Civil society groups say more than 240 people have been killed since President Pierre Nkurunziza sparked the unrest in April by saying he would seek a third term in office. He won a disputed election in July.

One police officer was killed and four others were wounded in clashes with gunmen during the night from Tuesday to Wednesday in Bujumbura’s Nyakabiga district, police spokesman Pierre Nkurikiye told Reuters.

Witnesses said two civilians were also wounded.

In the nearby Jabe neighbourhood, the body of a man was found. Police said he was killed elsewhere and his corpse dumped in the district.

Four other dead bodies were found in Mutakura and Cibitoke neighbourhoods. An official from the local administration said the victims had been beheaded. The official said they too may have been killed elsewhere as the district had been quiet overnight.

Residents of Mutimbuzi, which is outside the capital, said an unidentified man on a motorbike had thrown a grenade at a bar, killing two people and wounding three others.

Opponents have accused Nkurunziza of violating the peace deal that ended civil war and the constitution by serving another five-year term. A constitutional court ruled that the president could stay in office for another term.