Heavy gunfire was heard near Burundi’s state broadcaster RTNB on Tuesday with reports saying that one man has been critically injured.

The head of RNTB security, Lt.Col. Dismas Indaye, was attacked by unknown armed men a few minutes to noon, making him the second victim in less than 24 hours in what is appearing to be targeted attacks.

Last night, renowned human rights activist Pierre Claver Mbonimpa was injured by unknown gunmen near his home in the capital, Bujumbura. He was rushed to a nearby hospital where he is recuperating.

Mr Mbonimpa’s close relatives say he requires specialised medical treatment abroad but the government has allegedly refused to allow him to leave the country. He was a stern critic of President Pierre Nkurunziza's controversial bid for a third term in office.

This comes a day after the killing on a former Burundi intelligence chief and president Nkurunziza's aide Adolph Nshimirimana.

General Nshimirimana was killed in an attack on his car in Bujumbura. He was in charge of the president's personal security.

“Urgent investigation should be conducted in the killing of Gen. Nshimirimana within one week we should be able to bring the perpetrators to justice,” said President Pierre Nkurunziza.

Mr Mbonimpa is opposed president Nkurunziza's bid for the third term and played a major role in organising the street protests in Bujumbura.

Last year he was arrested by authorities for reporting that Imbonerakure militia were undergoing paramilitary training in DRC.

The African Union chair Nkosazana Dlamini-Zuma has called on Burundi's government to investigate the attempt murder of the human rights activist and the killing of Gen. Adolph Nshimirimana.

“It is so sad to learn of an attempt on the life of a civil society activist, the AU human rights and military observers are on the ground in Burundi to investigate following the unrest,” said Dr Zuma.

What appears to be “targeted assassinations” of key figures from both sides of the political divide is increasingly escalating following the confirmation of the president’s election last week.

Last night, heavy gunfire was heard overnight in the capital with unknown armed groups engaging the police.

“We heard some gunfire and shelling over the night, it was around 3am when I heard someone screaming,” said Nsavyimana Dieudone a local administrator in cibitoke.

“Early in the morning we found a dead body lying on the road,” he added.