Nigeria's defense chief says he hopes the pilots of a missing fighter jet are alive.

Two pilots and an Alpha jet have been missing since Friday when they left the northeast town of Yola on a bombing mission against Islamic extremists.

Chief of Defense Staff Air Marshal Alex Badeh told reporters Monday that the pilots had contemplated ejecting from the aircraft.

Farmers in Adamawa state reported seeing a low-lying aircraft in the mountainous Gombi region making so much noise it drew villagers out of their homes before it crashed near a primary school.

Badeh said citizens have been helpful but did not have enough information for them to pinpoint the aircraft's location.

He ruled out sabotage though Boko Haram extremists are known to have captured anti-aircraft weapons from the military.