Police in Rwanda say there have been two grenade attacks in the capital - one near Kigali's genocide memorial.
At least 16 people were wounded in the near-simultaneous blasts on Thursday night.
One person was killed in similar attacks last month in Kigali, blamed on two high-ranking officers now in exile.
Earlier this week, one of them - Lt Gen Faustin Kayumba Nyamwasa, a former chief of staff and ambassador to India - denied the allegations.
He told the BBC that the Rwandan authorities had staged grenade attacks and then accused him of being behind them.
Earlier he was stripped of his diplomatic post after the authorities accused him of supporting the opposition.
The BBC's Geoffrey Mutagoma in Kigali says police have not yet identified those responsible for Thursday's blasts.
Elections are due in Rwanda in August - and will be the second presidential polls held since the 1994 genocide in which 800,000 Tutsis and moderate Hutus were killed.
Lt Gen Kayumba Nyamwasa played an important role in the rebel Rwandan Patriotic Front (RPF), which put a stop to the killing and which is now in power.