Jerome Delay, Associated Press
A powerpoint presentation shows the preliminary results of Burundi's Presidential elections as they are being presented by the National Electoral committee in Bujumbura, Burundi, Friday July 24, 2015.

BUJUMBURA, Burundi — A Burundi general who was a key security ally of President Pierre Nkurunziza was killed Sunday in a drive-by shooting in the capital, Bujumbura, a presidential spokesman said.

Gen. Adolphe Nshimirimana, the president's senior adviser on security matters, was killed when men in a car shot at him and his bodyguards in the Kamenge neighborhood, Willy Nyamitwe told The Associated Press Sunday.

The attackers also lobbed a grenade into Nshimirimana's vehicle, he said. The general was taken from the car and later died from his wounds, said Nyamitwe.

The killing is likely to stoke tensions in Burundi, which has been wracked by violence since April when Nkurunziza sought a third term in office. Nkurunziza's bid to extend his time in power sparked frequent street protests in Bujumbura that were violently repressed by authorities. More than 100 people died in the unrest, and more than 100,000 people have fled the country fearing further violence.

Nshimirimana, a feared military officer who at different times served as army chief of staff and the country's intelligence chief, was widely seen as a key member of Nkurunziza's security team who helped put down an attempted coup in May.

There was no claim of responsibility for Nshimirimana's assassination and police did not comment.

Nkurunziza won the July 21 presidential polls with 69 percent of the vote.

The international community condemned the elections as not credible because of violence, intimidation, media restrictions and questions over the legitimacy of a third term for Nkurunziza.

Many fear that Nkurunziza's determination to stay in power will trigger increased violence in the poor central African country of 10 million that has a history of civil strife.

Last month the Burundi government said the army put down a rebellion in the country's north, killing 31 insurgents and arresting 171 others.