Boko Haram militants attacked a border village in northern Cameroon and are suspected of kidnapping at least 18 people traveling on a bus, two military sources told Reuters on Monday.

Nigeria's military is struggling to contain the Sunni jihadi insurgents blamed for killing 10,000 people last year and kidnapping hundreds of others while mounting frequent cross-border raids as it seeks to establish an emirate.

Neighbors Chad, Cameroon and Niger have responded by sending thousands of troops to the remote border zone near Lake Chad, where intense gunbattles erupted last week.

Two military sources said Boko Haram attacked the village of Kerawa in the far north on Sunday and 11 of their fighters were killed in clashes with Cameroon's army. They said at least eight Cameroonian soldiers were wounded in the fighting.

Separately, a passenger vehicle was missing near the village of Adanga Danga, the sources said.

"There are no claims yet but we think it was Boko Haram," said one of the sources, who said there were 18 people aboard.

The second military source said there were about 30 people on board the missing bus. A Defense Ministry spokesman was not immediately available for comment on the incidents.