text: However, it said the "masterminds" behind the murder of Gen Adolphe Nshimirimana were still being sought.
  Prominent human rights activist Pierre Claver Mbonimpa was shot and wounded in an apparent reprisal attack following Gen Nshimirimana's killing last week.
  Mr Mbonimpa has been allowed to fly to Belgium for treatment.
  Heavy shooting was heard in the capital, Bujumbura, on Sunday night, but it was unclear who was behind it, the AFP news agency reports.
  Burundi has suffered serious unrest since President Pierre Nkurunziza's decision in April to seek a third term in office.
  Opponents argued this violated the constitution, and protests broke out in parts of the country.
  There was also failed coup attempt in May, as renegade generals demanded that Mr Nkurunziza steps down when his term ends.
  A presidential election was held last month which Mr Nkurunziza won.
  The result was rejected by the main opposition parties, but one of its leading members, Agathon Rwasa, agreed to take the post of deputy parliamentary speaker to promote reconciliation.
  The prosecutor's office said in a statement that a military vehicle was used by Gen Nshimirimana's attackers and it was subsequently burned.
  "The identities of the perpetrators are now known. A certain number have been arrested. The rest of them and the masterminds are being sought," it  said.
  The attackers targeted the general's car with machine guns and rocket launchers in the Kamenge district of Bujumbura.
  He was widely seen as the most powerful person in Burundi after Mr Nkurunziza.
  Meanwhile, Mr Mbonimpa's daughter said the authorities had allowed him to leave for Belgium, the former colonial power.
  "He will be treated there and they can do all the tests that we can't do here. We are also more reassured about his safety there," Amandine Nasagarare said, AFP reports.
  The government condemned his shooting by a gunman on a motorbike last week as an act of "terrorism".
  Mr Mbonimpa was a staunch critic of Mr Nkurunziza's bid to run for office again, and was said to be one of the few members of Burundi's civil society who had not fled the country.
  In April, he was held without charge for more than 24 hours by the intelligence services after he called for protests against the president's efforts to secure a third term.
target: Several people have been arrested in Burundi over the assassination of a powerful general, the prosecutor's office has said.