The spiritual leader of Nigeria's Muslims was among the dead after a plane carrying at least 104 people crashed near Abuja, officials say.
The Sultan of Sokoto Mohammadu Maccido and his son, a senator, and other northern leaders were on board the ADC airlines flight to the city of Sokoto.
The plane crashed in a storm shortly after take-off, state radio said. Four people have reportedly survived.
This is Nigeria's third major air disaster in a little over a year.
The BBC's Alex Last in Nigeria says twisted, smouldering remnants of the plane litter the crash site on the edge of Abuja airport.
Eyewitnesses said they heard shouts for help from many survivors but they were unable to help because the plane was engulfed in flames.
Sokoto State government spokesman Mustapha Sheu said that the northern state's deputy governor, education commissioner and another senator were killed, along with the sultan and his son.
Sokoto State Governor Attahiru Bafarawa announced five days of mourning for the sultan and the other victims of the crash.
SULTAN OF SOKOTO
Leads Nigeria's 70m Muslims
Sokoto base for 19th Century jihad, spreading Islam across northern Nigeria
Sokoto still Nigeria's centre for Islamic learning
People have converged in front of the sultan's palace, some in tears.
The sultan is due to be buried shortly.
Nigeria's Supreme Council of Islamic Affairs (NSCIA) secretary-general Lateef Adegbite described the sultan's death as a tragedy, reports the AFP news agency.
"We are devastated by the tragic plane crash. It has left the Muslim faithfuls without leadership," he said.
"President Olusegun Obasanjo is deeply and profoundly shocked and saddened by the news of the reported air crash," presidential spokeswoman Oluremi Oyo said in a statement.
The president has ordered an investigation, she said.
After visiting the crash site, Federal Territory Minister Mallam Nasir el-Rufai told the BBC that the condition of the plane was "deplorable", with "bald tyres".
The government had already announced a major plan to overhaul the aviation industry and improve safety following last year's disasters, which killed more than 200 people.
Several airlines were grounded while safety checks were carried out.
ADC planes were not involved in last year's crashes.
The president himself blamed corruption and corner-cutting for poor safety standards.
Last month 10 senior army commanders were killed when their military plane crashed.
Our correspondent says that air travel in Nigeria has boomed in recent years, but this crash will raise further questions as to how these safety reforms are being implemented.
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