BAUCHI, Nigeria — Nigeria’s president called for calm on Sunday after at least 86 people died in clashes between farmers and semi-nomadic herders over the weekend.

Authorities imposed a dusk-to-dawn curfew in central Plateau state after the fighting, part of an escalation of clashes that have raged for years, often over dwindling fertile land.

A total of 86 people had died by late Sunday, state police spokesman Terna Tyopev said, raising the local government’s earlier estimate of 70.

The growing conflict by some accounts has become deadlier than Nigeria’s Boko Haram extremist insurgency.

Insecurity has become a major electoral problem for President Muhammadu Buhari, who plans to seek re-election in February and who won power on pledges to deliver peace and stability.

In a statement on the president’s official Twitter account late on Sunday, Buhari appealed for calm, adding that “no efforts will be spared to bring the perpetrators to justice, and prevent a recurrence.”

But senior lawmakers lamented the state of Nigeria’s law enforcement systems.

“This further strengthens my constant call for an overhaul of the entire security apparatus of this country,” Yakubu Dogara, the leader of Nigeria’s lower house of parliament, said in a statement on Sunday.

Buhari’s party rejects criticism that his administration is soft-peddling justice for the herders, who belong to the same Fulani ethnic group as the president.

Dramatic footage from Jos showed angry people waving machetes and sticks and shouting at passing security forces as they weaved around overturned and burning vehicles. Smoke rose in the distance. Women and children clutching overstuffed bags piled into the back of trucks, seeking a way out.

The deadly clashes between herders and farmers in central Nigeria are a growing security concern in Africa’s most populous country, which is roughly split between Muslims in the north and Christians in the south.

The threat from Boko Haram, which continues to carry out attacks in the northeast, has been cited as one cause of the growing tensions as herders — also feeling the effects of climate change — are forced south into more populated farming communities in search of safe grazing.

While few details emerged immediately of the latest killings, Nigerians for hours Sunday on social media shared a growing sense that something awful had occurred.

Earlier in the day the Plateau State governor announced a 6 p.m. to 6 a.m. curfew after saying had woken up to the “shocking news” of the attacks. He said the curfew affects the communities of Jos South, Riyom and Barkin Ladi “and is in effect until further notice.”

“Observe the curfew, observe the curfew and I will still remind them to observe the curfew,” he said. — Agencies