Nigerian militant group Boko Haram has reportedly killed dozens of people in five separate attacks on Nigerian villages, casting fresh doubt on a reported ceasefire deal announced Friday that was to set free 200 kidnapped girls, witnesses and security officials said Saturday.

The first two reported attacks targeted the villages of Abadam and Dzur, in northeastern Nigeria.

"I was just boarding a bus when the gunshots started," witness Adams Mishelia said of the Dzur attack, in a Reuters report. "People were fleeing into the bush, so I got off the bus and headed to the bush too. I later learned they slaughtered eight people."

The next three alleged attacks targeted villages in the government area called Michika, in Adamawa state.

"Dozens of people [have] been killed and houses [have] been burnt by the insurgents, so what is the meaning of the ceasefire the government is talking about?" state government legislator Adamu Kamale said.

The Nigerian government is urging caution, saying that it was not immediately clear whether the alleged attacks were carried out by Boko Haram or by another militant group. "The Boko Haram people have also said that some attacks were not undertaken by them," said government spokesman Mike Omeri.

The abduction in April of over 200 schoolgirls from the Nigerian town of Chibok sparked global outrage

Negotiations for girls' release ongoing

The violence has overshadowed the government's efforts to negotiate the release of more than 200 schoolgirls, whose kidnapping in April from the town of Chibok ignited an international uproar and sparked the #BringBackOurGirls Twitter campaign.

On Friday, Nigerian government officials announced a purported breakthrough ceasefire deal with Boko Haram that was to end the violence and set the schoolgirls free. On Saturday, government sources said they hoped to secure the release of the girls by as early as Monday or Tuesday.

But those close to the negotiations urged caution over the reported deal, as Boko Haram has yet to comment on the purported truce. The Nigerian government says its negotiations with the militant group are ongoing.

"We are negotiating with considerable caution. Boko Haram has grown into such an amorphous entity that any splinter group could come up disowning the deal. [But] we believe we are talking to the right people," a government source said.

The Nigerian government has struggled to combat the Boko Haram insurgency, which has claimed an estimated 5,000 lives

Boko Haram, whose name roughly translates as "Western education is sacrilege," communicates solely through videotaped messages by its alleged leader, a man known as Abubakar Shekau. But the Nigerian government is reportedly negotiating in neighboring Chad with a man named Danladi Ahmadu, who claims he is the group's "security general" and says he represents the group.

The Boko Haram insurgency has been characterized by a brutal campaign of bombings and shootings targeting Christian churches, Muslim mosques, schools, markets, bars, villages, police stations and a UN building. An estimated 5,000 people have been killed and a further 300,000 displaced by the violence.

bw/jm (Reuters, AFP, AP)