(Adds details on injured Italian nun)
BUJUMBURA, Nov 28 (Reuters) - Gunmen killed a Croatian nun and an Italian doctor who were working in a psychiatric clinic in northern Burundi, its head said on Monday.
Although the landlocked central African nation has been plagued by insecurity this year, the killings on Sunday night in the northern district of Kiremba were the first to target foreign aid workers since 2007.
"The armed bandits first cut the power and entered by force in the sisters' compound. They ordered the Croatian nun to give them money, and after that they shot her and she died immediately," said Father Rangoni Luciano from Italy, who works with the charity that runs the clinic.
The attackers kidnapped the Italian doctor, forcing him to drive them away, and later killed him, added Luciano. Local police confirmed the incident.
The Italian foreign ministry said an Italian nun was also seriously injured by gunfire in the attack. "(She) is receiving the necessary treatment in Kiremba hospital and her condition gives no cause for alarm," a ministry statement said.
Coffee-producing Burundi has enjoyed relative peace since a Hutu rebel group, Forces for National Liberation, laid down its weapons and joined the government in 2009 after almost two decades of war.
But attacks on civilians and soldiers have intensified since elections last year that were widely boycotted by the opposition. (Reporting by Patrick Nduwimana and Catherine Hornby in Rome; Editing by Duncan Miriri and Mark Heinrich)