A series of bombings and attacks claimed by a radical Islamist group has left "many'' dead and injured in northern Nigeria's largest city, a Nigerian Red Cross spokesman said.
Gunfire continued to echo through some areas of Kano on Saturday even though a strict curfew was imposed on Friday night and will remain in place until further notice, local officials said.
The attacks were a co-ordinated series of explosions and gunfire, some of which targeted police. At least 24 people have been reported dead but the death and injury toll continues to rise.
A correspondent with the AFP news agency has reported seeing at least 80 corpses in the morgue at Kano's main hospital, many with gunshot wounds.
In a statement issued late Friday, federal police spokesman Olusola Amore said attackers targeted five police buildings, two immigration offices and the local headquarters of the State Security Service, Nigeria's secret police.
"The police have commenced investigation and therefore use this medium to call for calm among the residents of Kano as police are doing their best to bring the situation under control," Amore said.
He added that police are "appealing to members of the public to come forward with information on the identity and location of these hoodlums. Information given will be treated with utmost confidentiality'.'
A witness told Al Jazeera that he had seen at least seven dead bodies, including five immigration officers and two civilians, following Friday's blasts.
Among those killed was a television reporter, Eneche Akogwu, 31, who was shot dead while interviewing witnesses.
In a statement released on Friday, Boko Haram said the blasts were revenge for the recent arrests of Boko Haram members in Kano.
"We are compelled to write this letter to inform Kano residents of this development," wrote Abubakar Shekau, the group's leader.
The country's police chief, Hafiz Ringim, has called for an investigation into the blasts, which he described as "well-co-ordinated attacks".
Ringim is under investigation himself, after a suspect charged with carrying out Christmas Day bombings on churches, escaped from police custody earlier this week. Some Nigerians have called for Ringim's resignation.
Ahmad Idris, Al Jazeera's correspondent in the capital, Abuja, reported that at least eight police stations were targeted in addition to the state police headquarters.
| Nigeria's president has declared a state of emergency in parts of four states hard hit by attacks [Reuters]
"Residents said there was sound of gunfire echoing in some parts of the city," he said.
Scores of bomb blasts in Nigeria's north have been blamed on Boko Haram.
Attacks specifically targeting Christians have also given rise to fears of a wider religious conflict in the country, with Christian leaders warning they will defend themselves. Some have even evoked the possibility of civil war.
Boko Haram also claimed responsibility for the August suicide bombing of UN headquarters in Abuja that killed 25 people.
Goodluck Jonathan, the Nigerian president, declared a state of emergency in parts of four states on December 31, hard hit by attacks blamed on Boko Haram.