A disgruntled soldier is suspected of gunning down eight other soldiers and three civilians at a military barracks in Cape Verde, the west African country's government says.
The suspected soldier is missing but there are "strong indications" he was behind the slayings on Tuesday, the former Portuguese colony's government said in a statement on its website.
The statement said "personal motives" inspired the attack, ruling out an attempted coup or any connection with violence associated with drug trafficking that has recently plagued the archipelago.
"People are advised to remain calm and serene," the statement said.
However, it also said officials had seized nine weapons and ammunition. It didn't elaborate on that find, nor did it say how it might be connected to the killings.
The three civilians killed included two Spanish technicians on assignment in Cape Verde, according to the government. The dead were all men aged between 20 and 51.
It said authorities are investigating what happened at the barracks that housed soldiers protecting a hilltop communications hub where the Spaniards and a Cape Verdean were reportedly working on repairs.
The government placed security forces on red alert at the international airport in Praia, the capital, and at the island's ports after the attack, the online service of newspaper Expresso das Ilhas said.
A policeman came across the bodies around midday, Cape Verde Television said.