Attacks on villages surrounding a central Nigerian city at the heart of unrest between Christians and Muslims have killed more than 50 people this week, officials said Saturday, as authorities pleaded for peace over the Easter holiday.

The attacks around Jos, a city in Nigeria’s fertile central belt, come as a string of unsolved killings continue to plague the region that has seen thousands killed in massacres in recent years. While a combined police and military force still patrols Jos and other parts of Plateau state, many of the villages attacked sit in remote, rural corners of the area that sometimes have only a single police officer on duty.

The most recent killings happened Friday night in the Barkin Ladi area, said Lt. Jude Akpa, a military spokesman. Attackers raided a village called Bokkos and killed nine people, fleeing before soldiers arrived, Akpa said. Emmanuel Lohman, a government official there, said gunmen armed with assault rifles struck a village called Ratas and opened fire during the night while many there were sleeping.

Witnesses said the shooting lasted for almost two hours before the attackers fled. The Christian villagers, who farm the fertile soils of Plateau state, blamed nomadic Hausa-Fulani cattle herdsmen for the attack. Such attacks remain common as Christian farmers clash with the herdsmen over land and grazing rights. Other attacks often are rooted in disputes over political and economic power in the region, which sits between Nigeria’s predominantly Muslim north and its largely Christian south.

Muhammadu Nura, the state secretary of a cattle breeders association, said Hausa-Fulani people had been killed in “reprisals,” but he denied that herders were involved the attacks.

In recent days, more than 50 people have been killed in attacks, witnesses and government officials say. Those incidents include an assault Wednesday on a village in the Riyom area that killed 28 people and an attack Thursday in the Bokkos area that killed 18 civilians. The military said its forces killed six people while trying to repel attackers in Thursday’s assault.

Jos and surrounding Plateau state have been torn apart in recent years by violence pitting its different ethnic groups and major religions — Christianity and Islam — against each other. Human Rights Watch says at least 1,000 people were killed in communal clashes around Jos in 2010, including attacks that saw whole villages killed.

— Associated Press