Two heavy explosions have rocked two different northern Nigerian cities frequently targeted by deadly attacks blamed
on Boko Haram, residents say.
It was not yet clear if there were any deaths linked to Monday's explosions in Kano, the largest city in Nigeria's north, and Maiduguri, a northeastern city.
Borno state, where Maiduguri is located, has been the epicentre of a violent campaign by Boko Haram, which is fighting Western influence and wants to form an Islamic state in Nigeria's north.
A blast outside a mosque near Kano's main textile market went off around 8:30am in an area where traffic police were stationed, residents said.
The area was later cordoned off by troops and policemen, an AFP news agency reporter saw.
"We just heard a loud explosion followed by billows of smoke and we realised that the traffic police that rest near the mosque and take turns in manning the traffic were the target," said a resident who lives in the area.
Residents of Maiduguri reported a huge explosion but could not provide any details.
"There was a very heavy explosion this morning that shook the entire city," a resident said.
'Slaughtered like sheep'
The blasts came after suspected Boko Haram members killed 10 Christians in a village called Chibok, in a remote part of Borno, on Sunday.
"Suspected Boko Haram came at night and set people's houses on fire before killing their victims," said Nuhu Clark, a former councillor of the village who escaped the attack.
A local government official, speaking on condition of anonymity, said "the attackers came in around 9pm chanting 'Allahu Akbar', which made us suspect they are Boko Haram. They moved into selected homes in the predominantly Christian part of the town and slaughtered 10 people like sheep".He said he counted 10 bodies afterwards.
A police spokesman said they were aware of the incident but were still trying to confirm casualties.
Armed fighters have killed hundreds of people since launching a rebellion against the government in 2009, the usual targets being security forces, government officials or Christians, whom Boko Haram sees as infidels.
Al Jazeera's Yvonne Ndege, reporting from Maiduguri, said there was fear among the people in the area.
"People are on edge and are constantly worried about violence. Maiduguri has been at the epicentre of violence, with criminal acts perpetrated by members of Boko Haram for at least two years now," she said.
"Almost on a daily basis we found, while on the ground there, that people witnessed suicide attacks, car bombings, churches being attacked, and major fighting between the armed group and a joint task force set up to fight Boko Haram."
In another development, security forces said on Sunday they had killed a senior Boko Haram commander, Mohammed Ibrahim, one of several who had a bounty placed on his head last week of 25 million naira ($158,900) in his case.
"He was killed in an operation in Gwange ward [Borno state] along with two of his unit commanders," a spokesman for joint military and police forces in Borno state, Lieutenant-Colonel Sagir Musa, said.
Attacks on Christians seem calculated to ignite sectarian tensions in Africa's most populous nation, which is split roughly evenly between Muslims and Christians.