"A (woman) kamikaze blew herself up near a mosque in Fotokol. A second one was neutralised and killed. It was obvious the two suicide bombers were targeting the mosque," a local source told AFP.
"Three civilians also died," added a security source who asked not to be named.
The attack was similar to others in the remote region bordering Lake Chad claimed by Nigerian Islamist group Boko Haram, and occurred 24 hours after two suicide bombers left two dead and 14 injured across the border in Chadian town Ngouboua on Sunday.
Both Ngouboua and Fotokol have come under attack several times from Boko Haram fighters in the past.
Monday's suicide attack, the 16th in Cameroon's far north since July, highlights the persisting threat of Boko Haram attacks in the Lake Chad area straddling the borders of Cameroon, Chad, Niger, Nigeria.
The group, believed to be hiding out in Nigeria's nearby Sambisa forest and the lake's many islands, is held responsible for 17,000 deaths and for making 2.5 million people homeless in its six-year campaign of violence.
Nigeria's new President Muhammadu Buhari has ordered his military commanders to end the unrest by the end of the year but around 1,300 people have been killed since he took office late May.