Nigeria’s Air Force said one of its planes crashed in central Nigeria with the country’s army chief Ibrahim Attahiru on board.

Nigeria’s top soldier, Lieutenant General Ibrahim Attahiru, died during an official trip to the country’s Kaduna State when his plane crashed on Friday, Air Force spokesman Edward Gabkwet said.

The spokesman acknowledged that one of its planes was involved in a crash near Kaduna International Airport, some 180 kilometers (112 miles) north of the capital, Abuja.

“The immediate cause of the crash is still being ascertained,” Gabkwet said.

Attahiru took over as army chief in a major military reshuffle in January. Nigeria has been facing insurgencies from Boko Haram and Islamist State-affiliated militants, as well as separatist Indigenous People of Biafra group (IPOB). Additionally, security forces are struggling to respond to kidnappings and other security threats by well-organized groups of bandits. President Muhammadu Buhari appointed Attahiru and three other top military leaders in an attempt to curb the violence.

Buhari called the crash a “mortal blow … at a time our armed forces are poised to end the security challenges facing the country.”