Nigeria's army chief, Lieutenant General Ibrahim Attahiru, died in an air force plane crash on Friday.
He was on an official visit to the northern state of Kaduna, which has had security challenges in recent months.
The air force said in a statement that its plane crashed near Kaduna airport and that it was investigating the cause.
The presidency added that other military officers were also killed in the crash.
President Muhammadu Buhari, in a presidency statement, described the crash as a "mortal blow ... at a time our armed forces are poised to end the security challenges facing the country."
Nigeria, Africa's most populous nation, has had poor air safety record in the past, although it has improved in recent years.
Buhari appointed Attahiru alongside other military chiefs in January after years of mounting criticism over spreading violence by insurgents and armed gangs.
The World Court has unanimously ordered Israel, accused by South Africa of genocide in Gaza, to take all necessary and effective action to ensure basic food supplies to the enclave's Palestinian population and halt spreading famine.
Russian missile and drone attacks hit thermal and hydro power plants in central and western Ukraine, power grid operator Ukrenergo said on Friday, the latest assault on the already damaged power infrastructure.
A bus crash in South Africa's northern province of Limpopo resulted in 45 deaths and one serious injury, the country's Department of Transport said on Thursday.
Spanish coastguards rescued 124 migrants, including young children and a person needing a wheelchair, from two wooden boats in the seas off the Canary Islands on Thursday.
Twelve people drowned trying to reach aid dropped by plane off a Gaza beach, Palestinian health authorities said, amid growing fears of famine nearly six months into Israel's military campaign.
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