Two women carried out the attack late on Wednesday as they walked into a busy area in the centre of Waza, a small town 8km from the Nigerian border, local authorities said.
The bombers struck an area with "restaurants, telephone cabins and kiosks", a local official told the AFP news agency on Thursday.
"The town has been sealed off. Nobody can enter and nobody can leave," the official said, adding that some of the wounded were in "quite serious" condition.
Midjiyawa Bakari, the governor of the Far North region where the attack took place, said a baby was among those killed.
An army colonel who was responsible for evacuating the wounded told Reuters news agency that the attack was "perpetrated by one suicide bomber, and the other was shot dead".
No group has claimed responsibility for the attack, but the region has been a frequent target of Boko Haram fighters in recent years.
Last month, nine were killed in the town of Kolofata when two children carrying explosives blew themselves up near a camp housing people displaced by Boko Haram violence.
An "alarming" number of children in Africa, most of them girls, have been used as suicide bombers by Boko Haram in 2017, according to UNICEF.
Some 200,000 Cameroonians from the Far North region have fled their homes in fear of the violence.
At least 20,000 people have been killed and more than 2.6 million made homeless in the Lake Chad region, which includes Nigeria, Cameroon, Chad and Niger since the start of Boko Haram's armed campaign in 2009.
On Tuesday, suicide bombers killed at least 15 people and wounded 21 others in the northeast Nigerian city of Maiduguri in Borno state.
Nigeria's government and military maintain that Boko Haram is a spent force, but intermittent attacks and suicide bombings pose a constant threat, particularly in remote areas.
Boko Haram this week released a video showing executions and amputations, suggesting it still holds territory in some areas.