A leading rights activist in Burundi was shot and wounded late Monday by unknown assailants in the capital, Bujumbura, a civic leader said.

Pierre Claver Mbonimpa, president of The Association for the Protection of Human Rights and Detained Persons, was fired upon while walking home, said Vital Nshimirimana. Mbonimpa was being treated in a local hospital, he said, offering no more details.

The shooting came a day after the assassination of Adolphe Nshimirimana, a top military general who was a close ally of President Pierre Nkurunziza. Nshimirimana was killed in a drive-by shooting early Sunday in Burundi.

There is fear that Nshimirimana’s killing could spark revenge attacks against perceived opponents of the regime.

Gunfire rang out in Bujumbura Sunday night following the killing of Nshimirimana.

Burundi has been on edge since April after the ruling party nominated Nkurunziza to be its candidate in presidential elections, setting off frequent and often violent street protests in Bujumbura.

Nkurunziza, who was re-elected last month, said in a televised address that he has ordered the police to find Nshimirimana’s killers within 10 days.

Nshimirimana, a former army chief of staff and head of the intelligence services, is believed to have helped to defeat an attempted coup against Nkurunziza in May.