Two bombs exploded near a bus station in the central city of Jos on Thursday evening, witnesses said, and the second one killing at least 40 people.
Casualties from the first blast could not immediately be ascertained and security sources could not immediately be reached for comment.
Bomb blasts that bore the hallmarks of Islamist Boko Haram militants killed 118 people in the same area of Jos in May.
“I saw a flash of light and heard a loud boom. Afterwards, there was debris everywhere and mutilated bodies,” witness Tanko Mohammed said of the blast in Jos’s commercial Terminus district.
Boko Haram is a Sunni jihadist movement that has been waging a five-year insurgency to establish an Islamist state in the northeast of the country.
President Goodluck Jonathan declared a state of emergency in three north-eastern states last year. The number of attacks has risen sharply since then, in the run-up to elections in February 2015.