Since it began a decade ago, Nigeria's Boko Haram insurgency has killed more than 27,000 people, displaced some two million, but has increasingly spilled over into neighbouring Cameroon, Chad and Niger.
"Boko Haram attacked around 2300 (22:00 GMT) in Mbreche district, about 30 kilometres (20 miles) from the Nigeria border. They kidnapped 21 people, but four managed to escape," a local official said.
A police official confirmed the kidnapping of the 17 young people, both male and female, who range from ages 11 to 20.
"The army has launched a rescue operation. Among the four people who got away, one says he recognised the kidnappers as Mbreche inhabitants who were recruited by Boko Haram," the official said.
Since 2014, Cameroon says militant attacks on its territory have caused "several thousand" deaths. The insurgency has forced more than 250,000 people to flee their homes as well as trigger an influx of 60,000 Nigerian refugees.
Boko Haram has since split in two, with the emergence of a branch that has sworn allegiance to the Islamic State (IS) group, known as Islamic State Group in West Africa or ISWAP.
The other faction, loyal to the movement's historic leader, Abubakar Shekau, is known for targeting civilians, including village attacks and suicide attacks.
The ISWAP, which has about 3,000 men grouped at Lake Chad, has been building its capacity and mainly targets the army.
Militants often make incursions into Cameroon in search of food reserves, such as livestock, and to kidnap women and children for ransom or to be forcibly recruited.
Boko Haram also targets the soldiers of the Cameroonian army.
The country also faces a serious crisis in its English-speaking areas, the North-West and South-West regions, where for two years separatists and the army have fought a conflict , killing more than 3,000 people.