Scores of people are dead after vicious weekend clashes in central Nigeria between mostly Muslim herders and Christian farmers.
One report has claimed 86 people were killed in the conflict, which by some accounts has become deadlier than Nigeria's Boko Haram extremist insurgency.
Footage from Jos showed angry people waving machetes and sticks shouting at passing security forces as they weaved around overturned and burning vehicles.
Women and children clutching overstuffed bags could also be seen piling into the back of trucks, seeking a way out.
It is very, very, unfortunate that an incident is happening again like this
President Muhammadu Buhari warned against reprisals after the "deeply unfortunate killings across a number of communities" in central Plateau State as the military and police tried to end the bloodshed, saying "no efforts will be spared" to find the attackers.
Nigeria's government has not announced a death toll. The independent Channels Television cited a Plateau State police spokesman, Mathias Tyopev, as saying 86 people had been killed, with at least 50 houses destroyed.
"Please remain calm," said the Plateau State governor, Simon Bako Lalong, as a helicopter flew overhead. "It is very, very, unfortunate that an incident is happening again like this."
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 north-east, 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.
The widespread security issues pose a major challenge to Mr Buhari, a Muslim former military ruler who won office in a democratic transfer of power in 2015, as elections approach next year.
While few details emerged immediately of the latest killings, Nigerians on social media shared a growing sense that something awful had occurred.
Earlier in the day the Plateau State governor announced a 6pm to 6am 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.
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