At least 12 people have been killed and 48 others wounded in a double suicide attack at a market in Nigeria's Maiduguri city, residents and an emergency official said Wednesday.

Ibrahim Usman, a trader in Muna Garage market, says the attack happened Wednesday afternoon. He says the first bomber attacked inside the market while the other remained outside, killing only himself.

The head of rescue operations for the State Emergency Management Agency, Bello Dambatta, says a female bomber attacked the market while the other attacker was male.

Muna Garage, the site of a camp for displaced people, has been attacked several times in the past few years by Boko Haram insurgents.

Boko Haram, which was formed in Maiduguri, has killed more than 20,000 people in its nine-year insurgency.