Updated

Gunmen surrounded villages in northeast Nigeria and set them ablaze, killing at least 12 people and wounding 48 others in violence that could spread as attackers remain hiding in the rural region, the Nigerian Red Cross said Monday.

The attacks targeted four villages early Sunday morning in a remote area of Adamawa state, which borders Cameroon. The number of dead could rise as relief workers remain unable to reach the villages affected and about 2,000 people have fled, the Red Cross said in a report obtained by The Associated Press.

Volunteers "could not get safe access to these affected communities as the gunmen are said to be in the bush around the communities changing plans," the report read. It estimated as many as 100 gunmen attacked the villages.

The dead included at least one police officer, the report read. Those injured suffered gunshot and machete wounds.

Relief workers had warned this weekend that people had begun fleeing the Lamurde local government area as rumors of an attack spread through the villages. The attack likely is a reprisal from Hausa Fulani cattle herdsmen over them being attacked over another killing earlier this year, the Red Cross said.

Soldiers apparently had surrounded the area by Monday. Yushau Shuaib, a spokesman for Nigeria's National Emergency Management Agency, said Monday that officials were aware of the violence, but had no further details.

Adamawa state police spokesman Nemuel Yoila said the attack appeared to pit the Fulani cattle herders against the Pere people who live in the area, one of Nigeria's more than 250 ethnic groups. Yoila said the fighting occurred near a group of paramilitary police officers who were unable to stop the attack.

Yoila said only six people had been killed, contradicting the Red Cross report. However, police and military officials often underreport casualties in Nigeria to downplay the severity of attacks.

"Normalcy has been restored to that area," the spokesman said.

Nigeria, a multiethnic nation of more than 160 million people, often sees outbreaks of violence across religious lines. However, the attacks often find their root in political and economic problems. Meanwhile, the nation is facing increasingly bloody sectarian attacks from a radical Islamist sect known as Boko Haram.

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Jon Gambrell can be reached at www.twitter.com/jongambrellap.