Weekend raids by gunmen in a central Nigerian state left more than 100 dead, an official said on Monday, as the governor widened a curfew to restore calm in the flashpoint area.
Plateau state falls in Nigeria's so-called "Middle Belt," where the mainly Christian south meets the majority Muslim north and has been the site of waves of sectarian violence in recent years.
The weekend attacks were blamed on gunmen from the Fulani, a pastoralist, Muslim ethnic group with long-standing land rights grievances and resentment against the state's mostly Christian leaders who control political power.
At least 80 died when Fulani herdsmen raided several villages on Saturday, the spokesman for the state's governor, Pam Ayuba, told AFP.
On Sunday, they stormed a graveyard roughly 90 kilometres (56 miles) from the state capital, where some of the victims of the previous day's attack were being buried, Ayuba added.
Among those killed in the graveyard assault were federal senator Gyang Dantong, majority leader of the state's legislature Gyang Fulani, as well as at least 20 others, Ayuba further said.
Both politicians were members of the mostly Christian Birom ethnic group, officials and police said.
Nigeria's Senate President David Mark, the country's third ranking political official, called the attack an "assassination".
"As a nation, we must just rise against those who are determined to return us to a state of nature where life had little or no value," the statement from his office said.
After news of the killings spread, mobs set up roadblocks in several areas, prompting to Governor Jonah Jang to impose an immediate dusk-to-dawn curfew in four districts.
That curfew was extended on Monday, with residents only allowed out between midday and sundown.
In a broadcast aired on local radio and television late Sunday, officials said businesses should remain closed for the next two days as security services attempt to pacify the chronically-troubled state.
The recent bloodshed in Plateau has been caused by several concurrent conflicts.
Aside from the Fulani violence, the divided state has seen sectarian violence between Muslim and Christian groups, much of it concentrated around Jos.
Boko Haram, the radical Islamist group that is responsible for more than 1,000 deaths in Nigeria since mid-2009, has also targeted the area, including by attacking churches.
Last month in neighbouring Kaduna state, coordinated church bombings by Boko Haram sparked reprisal violence by Christian youths who raided mosques and killed dozens of their Muslim neighbours, burning some of their bodies.
Muslim groups responded the next day and killed several others.
Kaduna remains under partial curfew as tension persists in the state capital Kaduna city, one of the few religiously divided cities in Nigeria's mainly Muslim north.
The wealthier, southern half of the country is mostly inhabited by Christians.
Nigeria is Africa's most populous country with an estimated 167 million people, and the continent's top oil producer.