Witnesses say four people were killed overnight in the Burundian capital of Bujumbura as violence persists following the controversial re-election of President Pierre Nkurunziza.

Witnesses in the the volatile neighborhood of Musaga said the four friends were shot and killed in a bar, an apparent revenge attack against members of the ruling party.

Musaga resident Pascal Nsengiyumva said it was "horrible to wake up with people killed beside us."

The bodies were still at the crime scene Wednesday morning as residents waited for the police to arrive.

Bujumbura has been hit by violence since April, when the ruling party declared it had picked Nkurunziza to be its candidate in presidential elections to serve a third term.