A twin bombing in a crowded market in the Nigerian city of Jos killed at least 31 people on Thursday.

The Islamist militant group Boko Haram, which fights to impose an Islamic state in the West African country, has taken to targeting civilians in bombings and suicide attacks that "kill dozens at a time in crowded city markets, colleges and bus stations," according to the Los Angeles Times. Although the group hasn't taken responsibility, the attacks are simimlar to previous ones conducted by Boko Haram.

Thursday's incident came came a day after two female suicide bombers killed four at a popular textile market in the northern city of Kano.

The number of casualties in the Jos, meanwhile, could rise even beyond those already confirmed dead, authorities warned.

"The bodies recovered so far are 31, but rescue workers are at the scene and the figures may change," said Pam Ayuba, a spokesman for Plateau state Gov. Jonah Jang.

Witnesses told The Guardian the dead had been ferried to morgues across the city.

Resident Muhammed Wase said youths armed with sticks confronted security officials whom they accused of providing insufficient protection.

"In the time it took for the police and military to reach the blast site, we had already evacuated two bodies. They didn't help us at all when they arrived," Wase said. "We ordinary people on the streets are dying, and nobody in government is interested."

The blasts occurred in the evening as store owners were closing their stores and Muslims were preparing for prayers, Al Jazeera reported.

Abdulsalam Mohammed, a spokesman for the National Emergency Management Agency, said officials were looking for other explosive devices that may have been left in the area.

"[The bombing] underlin[es] growing insecurity as Africa's most populous country gears up for elections eight weeks away," according to The Guardian.

They occurred only hours after former military ruler Muhammadu Buhari announced that he would challenge President Goodluck Jonathan in the upcoming February election.

More than 118 were killed when bombs exploded in the same neighborhood in May this year, and the insurgency has already claimed the lives of some 10,000 this year alone.