The attack was carried out in Gamboru town on Wednesday, barely three weeks after Boko Haram fighters were dislodged by Chadian soldiers on regional cooperation, Xinhua reported citing the security source.
Some Cameroonian soldiers moved to repel the attack but not after the 10 people had been killed, the source said, noting the incident occurred at 4:50 p.m.
A local resident named Mohammed Gaji said that the casualties were recorded in Foyi and Ngala communties near Gamboru. More residents might have been killed during the gun fight between Cameroonian soldiers and the terrorists, he added.
Wednesday's attack occurred as Nigerian forces pushed out Boko Haram fighters from most of the communities initially captured and occupied by the insurgents ahead of Nigeria's March 28 presidential poll.
Boko Haram seeks to enshrine the Islamic Sharia law in the constitution of Nigeria.