Parts of two districts in Burundi's capital, Bujumbura, have been temporarily sealed off after fighting killed four people.

People have been seen fleeing the affected districts to find shelter elsewhere.

The killings are part of a cycle of violence that began in April with protests against President Pierre Nkurunziza's third-term bid.

The president has pledged to crack down on those behind the trouble.

People are leaving the restive districts fearing what could happen next

In Wednesday night's violence, officials say two people were killed in an exchange of gunfire with police.

A third person was killed by gunmen - described by police as "insurgents" - and it is not yet clear what caused the death of the fourth person.

The districts of Mutakura and Cibitoke were well known for their demonstrations against Mr Nkurunziza's plan to run for the presidency again.

In July, he won a third term which opponents described as unconstitutional.

President Nkurunziza survived a coup attempt in May

Since then, there has been a series of killings of supporters and opponents of the government, including the assassination of a senior general.

Analysts say that in some areas of the capital, street protests have now turned into armed resistance.

The president has given people who hold illegal weapons until Saturday to give them up, otherwise he has said security forces will use all means available to end the situation.

The BBC's Prime Ndikumagenge in Bujumbura says that those fleeing the affected areas were carrying mattresses and cooking pots as they left.

Some of them told him they were leaving because of what they feared could happen after Saturday's deadline passed.