Seven foreign workers were kidnapped late Saturday from a construction company in northeastern Nigeria, police said.
The workers include one Italian citizen, one Greek citizen and two Lebanese citizens, according to those governments. Nigerian police said a Briton was also kidnapped; British authorities said they were aware of such reports and were making inquiries.
The workers were taken Saturday night from the offices of Setraco, a construction company in Jama'are, in Bauchi State, police said. The company is based in Abuja and is involved in many major road construction projects in northern Nigeria.
The gunmen first attacked a prison, burning two police trucks, public service broadcaster Voice of Nigeria reported, citing state police spokesman Hassan Muhammed.
They then killed a guard at the Setraco workers camp before kidnapping the workers, Muhammed told the broadcaster.
Nigeria has seen a rash of killings and kidnappings blamed on criminal groups or the Islamist militant group Boko Haram.
A week ago, three North Korean doctors were killed at a hospital in northern Yobe state, the state police chief told CNN. Ten suspects were arrested.
Earlier this month, nine people working for a government polio vaccination program were killed in the northern city of Kano, a police spokesman said.
Nigeria launched a military crackdown on Boko Haram on New Year's Day. Security forces have since captured one of the group's leaders and killed 17 suspected Boko Haram members in a two-day offensive.
Human Rights Watch says Boko Haram -- whose name means "Western education is sacrilege" -- has killed more than 2,800 people in an escalating campaign to impose strict Islamic law on largely Muslim northern Nigeria.