A bomb injured four people in a market Sunday in Maiduguri, a day after the northeastern Nigerian city was hit by a suicide bomber who killed 16 in a mosque. The explosion on Sunday was near the Nigeria Customs House in Maiduguri, AP quoted Jafar Aminu - a trader at Gamboru market - as saying. Nigeria's extremists, Boko Haram, are suspected for the explosion. "The explosion did not kill anyone but injured four persons among whom one has his arm completely ripped off by the blast," said Aminu.