BAUCHI, Nigeria — Police in northern Nigeria say gunmen have kidnapped seven foreign workers from a construction company.

The attack happened in Bauchi state overnight Saturday. Police spokesman Hassan Muhammed told The Associated Press that the attack first targeted a prison in the area.

Muhammed said Sunday the attackers then went to the construction company STRAECO, where they killed a guard and kidnapped the foreign workers.

The nationalities of the workers were not immediately known.

Nigeria's predominantly Muslim north has been under attack by the radical Islamic sect known as Boko Haram in the last year and a half. The country's weak central government has been unable to stop the group's bloody guerrilla campaign of shootings and bombings.