More than 250 Kenyans have gone to fight for Russia in Ukraine, mostly willingly, Kenya's foreign minister says.

The suspect is in custody but his motive is unknown, the police say in a brief statement.

Human Rights Watch says Capt Traoré, other military leaders and jihadists "may be liable" for the killings.

Powerful blasts destroyed homes and sparked panic in the city of Bujumbura on Tuesday night.