A witness says a bomb injured four people in a market in Maiduguri in northeastern Nigeria, a day after a suicide bomber killed 16 in a mosque in the same city.

Jafar Aminu, a trader at Gamboru market, said the explosion on Sunday was near the Nigeria Customs House in Maiduguri. Nigeria's Islamic extremists, Boko Haram, are suspected for the explosions.

An official of a self-defence group in Maiduguri, Abbas Gava, said the explosive may have been concealed in some sacks of charcoal. He said one of the injured lost a hand. He said Gamboru market has suffered several such attacks in the last three years.