Witnesses say suspected Boko Haram militants dressed as Nigerian soldiers killed 19 people Sunday at a fake checkpoint near the border with Cameroon.
Survivors and others near the scene say 19 bodies, including those of two truck drivers, were recovered at the ambush site about 30 kilometers from the border near the town of Logumani.
The leader of a civilian vigilante group aligned with the government told the French News Agency his group found five of the victims shot dead, while the remaining 14 were hacked to death.
Other reports quoted witnesses as saying the killings only stopped when the attackers sped off on motorcycles after one of them received a phone call while the slaughter was under way.
Boko Haram Islamists have been fighting since 2009 to impose a strict form of Islamic law on Nigeria's Muslim-majority north.
The militants have been blamed for thousands of deaths, and continue to launch attacks in the northeast, despite an all-out government military offensive ordered by Nigerian President Goodluck Jonathan in May.
Analysts say the government offensive, including airstrikes, ground attacks and the use of locally organized civilian militias, has driven the militants into the remote northeast, where they appear to be regaining strength.