Extremist fighters killed eight people including soldiers in multiple attacks in northern Cameroon on Tuesday, a regional official said.

Fighters with Boko Haram killed three customs officers, three soldiers and two civilians in separate attacks in the towns of Mora and Zigage on the border with Nigeria, said Midjiyawa Bakari, governor of the region.

“The Boko Haram fighters are in huge numbers along the border with Nigeria and we are counting on collaboration between the military and civilians to stop this new wave of attacks,” he said. Several people were wounded and have been hospitalized, Bakari said.

Boko Haram is a homegrown extremist group in Nigeria that launched an insurgency in 2009 to fight against Western education and to establish Islamic Shariah law in the country’s northeast. Their rebellion has spread over the years to neighboring West African countries, including Cameroon, Niger and Chad. The insurgency has killed more than 36,000 people mainly in Nigeria, and displaced around 3 million, according to the United Nations.

Cameroon’s government said that Boko Haram fighters crossed into the country from Nigeria in large numbers on Monday evening before carrying out the attacks. Cameroon’s military has been deployed to protect civilians on the border.