A Cameroonian soldier was killed and 10 Chinese nationals were feared kidnapped after an overnight attack in northern Cameroon believed to have been carried out by Boko Haram militants from Nigeria, police said Saturday.

"Boko Haram Islamists attacked a camp (of road workers)... Ten Chinese cannot be found since the attack. We think they have probably been kidnapped," a local police chief said on condition of anonymity.

A police officer and a detainee were shot dead overnight in an attack in northern Cameroon blamed on Nigerian Islamist extremist group Boko Haram, a security source said Monday.

"Boko Haram attacked the unit in the night. (The attackers) were looking for a detained member. They left with him and with other people who were in the same cell" of the paramilitary police in Kousseri, said the source, who asked not to be named.

Cameroon's security forces Sunday were sweeping the remote northern region where two Italian priests and a Canadian nun were kidnapped by suspected Boko Haram gunmen, a local government official said.

"We are everywhere. We have been on the ground since the abduction," local governor Awa Fonka Augustine told Agence France Presse without elaborating.

Suspected Boko Haram gunmen seized two Italian priests and a Canadian nun in northern Cameroon overnight Saturday, in the latest kidnapping of Westerners in the remote, insurgency-wracked corner of west Africa.

The attack occurred overnight in the small parish of Tchere, which lies about 40 miles (60 kilometers) from the corner of northern Nigeria that serves as a base for the Islamist Boko Haram group.

Boko Haram leader Abubakar Shekau likely has little control over his fighters, the International Crisis Group said on Thursday, calling the Islamist terror group "more dispersed than ever".

A new report from the Brussels-based think-tank said many of Boko Haram's senior commanders are probably based outside Nigeria, including in neighboring Cameroon and Niger.

Cameroon said on Thursday it had arrested three suspected arms dealers believed to be linked to Nigeria's militant Islamist group Boko Haram.

The men were caught in the far north of the country on Wednesday, near the border with Nigeria where the group has been waging a brutal armed insurgency.

Seven people were killed on Sunday when Boko Haram militants launched an assault in northern Cameroon, a Cameroonian security source said.

"Boko Haram killed a (Cameroonian) soldier. Our soldiers killed six of their guys" and "captured" two others near the Nigerian border, the source told Agence France Presse on Monday, requesting anonymity.

Nigeria's presidency on Friday said the country was at war with Boko Haram, apparently backing off previous claims that the Islamist rebels were on the run and desperate.

President Goodluck Jonathan's administration has been fiercely criticised over its handling of the conflict, both for its inability to stop massive attacks on defenseless civilians and for what some have described as mixed and contradictory messages on the severity of the crisis.

Scores of suspected Boko Haram Islamists armed with grenade launchers and explosives razed a town in Nigeria's embattled northeast, killing two people, including a child, witnesses told Agence France Presse on Thursday.

Residents in Michika, in Adamawa state, said people fled to the nearby foothills when the attackers dressed in military uniforms stormed the town in four-wheeled drive trucks and motorcycles.

Nigeria has sealed a portion of its northeastern border with Cameroon to block the movement of insurgents and other criminal groups, the military said Sunday.

The closure has been imposed in Adamawa state, one of three states in the northeast placed under emergency rule in May following waves of attacks by Boko Haram Islamists.