Blast injures 4 in Nigerian city, day after attacks kill 30

May 31, 2015: People inspect houses damaged damaged in Saturday's rocket propelled grenades by Islamic extremist in Maiduguri, Nigeria. (AP Photo/Jossy Ola)

MAIDUGURI, Nigeria – A bomb in a market tore off a man's arm and injured three other people in Maiduguri on Sunday, a day after the northeast Nigerian city was hit by dozens of rocket-propelled grenades and a suicide bombing which together killed 30 people.

The targeting of the biggest city in northeast Nigeria comes two days after Nigeria's newly inaugurated President Muhammadu Buhari said he is moving the headquarters for the military's fight against the Islamic extremists from the capital Abuja, in central Nigeria, to Maiduguri. The city also is capital of Borno state and the birthplace of Boko Haram.

The Sunday blast came from explosives concealed under bags of charcoal, said trader Jafar Aminu at Gamboru market.

"The explosion did not kill anyone but injured four persons including one whose arm was completely ripped off by the blast," Aminu said.

Gamboru market has suffered several such attacks that have killed dozens of people in the past three years.

Thirteen people died in Maiduguri on Saturday when Boko Haram fighters fired rocket-propelled grenades into homes on the western outskirts, according to witnesses. It's a new terror tactic that destroyed several homes, the witnesses said.

Later Saturday a suicide bomber detonated himself outside a Maiduguri mosque, killing 16 other people.

The nearly 6-year-old Islamic uprising in northeastern Nigeria has killed an estimated 13,000 people. Maiduguri's population of 2 million has swelled with hundreds of thousands of refugees who have been forced from their homes.

A multinational offensive this year forced the insurgents from towns where they had declared an Islamic caliphate but suicide bombings and hit-and-run attacks continue.

Nigeria's military says Boko Haram's main fighting force is trapped in the northeastern Sambisa Forest. But the insurgents keep attacking Maiduguri, which is 125 miles away.

Also Sunday, the insurgents attacked Fika town in neighboring Yobe. They killed no one but burned down several government offices and looted shops, said shop owner Modu Fika.