Three girls carried out suicide bombings in the northeastern Nigerian city of Damaturu on Friday, killing 13 people celebrating the end of the holy Muslim month of Ramadan, police said.

"Thirteen people were killed in the... suicide blasts," said Markus Danladi, Yobe state police commissioner. "The attacks were carried out by three underage girls. Fifteen people were also injured in the attacks."

Twin blasts rocked a market in the northeast Nigerian city of Gombe on Thursday, leaving several people dead, witnesses said, in the latest slew of violence likely linked to Boko Haram jihadists.

The first explosion took place outside a packed footwear shop around 1620 GMT, followed by a second explosion just minutes later, said Badamasi Amin, a local trader who counted at least three bodies.

At least 30 people were killed in three attacks by Islamists in northeastern Nigeria, local officials and inhabitants said Wednesday.

The three assaults were carried out simultaneously Tuesday. In the deadliest, over 20 were killed outside Ngamdu, a local legislator, Mohammed Sando, told AFP.

Boko Haram gunmen killed dozens of people in four villages in northeast Nigeria, slitting some residents' throats and opening fire on others, one resident and the police said on Tuesday.

The atrocities near Monguno in the northeastern state of Borno took the death toll since Muhammau Buhari became president in late May to more than 625, according to an AFP count.

Nigerian President Muhammadu Buhari on Monday sacked his entire military top brass, his spokesman said, in a widely expected move as he wrestles with an insurgency by Boko Haram Islamists.

"The President has relieved the service chiefs, including the heads of the army, air force and navy of their appointments," Femi Adesina told AFP.

A suicide bomber hit a military checkpoint on the outskirts of the northeastern Nigerian city of Maiduguri on Monday, in the latest in a string of attacks blamed on Boko Haram Islamists.

The blast happened at about 12:10 pm (1110 GMT) at the Jimtilo checkpoint, as passengers arriving in Maiduguri were being screened, two civilian vigilantes told AFP.

Gunmen suspected to be gang members shot dead five local residents at the weekend near Nigeria's oil city of Port Harcourt, the police said on Monday.

Rivers state police spokesman Ahmad Mohammed said assailants on motorbikes opened fire on Sunday in the Agbonchia Eleme area, near the country's largest oil refinery.

United Arab Emirates police have busted a cell of three Nigerian hackers who targeted U.S. bank accounts, the interior ministry said Sunday.

The trio were arrested following a tip-off from police in California about "cyber-criminal activity based in the UAE," a statement said.

Boko Haram on Saturday claimed responsibility for attacks in Chad's capital N'Djamena and the Nigerian city of Maiduguri, the SITE Intelligence Group said.

The U.S.-based monitoring group said the claim of responsibility, made on Twitter, was signed "Islamic State, West Africa Province", as Boko Haram has styled itself since pledging allegiance to the Islamic State group in March.

At least 14 people were killed in a suicide bomb attack at a crowded market in Chad's capital on Saturday just days after Boko Haram claimed a previous bombing in the city that left 38 people dead.

The attack in N'Djamena by a man disguised as a woman in a full-face veil came after a botched bombing in the capital of Nigeria's Borno state, Maiduguri, which killed two pedestrians.