Police in Nigeria's central Plateau state say they have sent extra officers to nine villages where gunmen on Sunday reportedly killed more than 70 people and burned down houses. Police and locals say hundreds of villagers have fled their homes since then. Attacks by armed gangs are becoming increasingly common in northern and central Nigeria.

The Plateau State Police public relations officer, Gabriel Ubah, tells VOA that police have sent reinforcements to the affected villages including Kukawa, Giyanbahu, Dangur and Keren.

"We're doing our possible best. Security operatives will be deployed to the areas and we've also renewed our strategies which will not be made known to the public. It's an in-house security strategy that has been put in place," he said.

Ubah said police have yet to determine the number of casualties from the attacks. Local residents say more bodies were discovered Monday.

Armed gangs invaded the villages in broad daylight on Sunday, shooting sporadically and torching houses. Local residents say the victims included farmers who were tilling their fields in preparation for planting. They say the attackers abducted dozens of people, including women and children.

The attacks occurred barely one week after 17 people were killed elsewhere in Plateau during a festival held to pray for peace and a bountiful harvest.

No one has claimed responsibility for the attacks.

Attacks by marauding armed gangs in northwest and central Nigeria are becoming more common, causing widespread criticism of the Nigerian government.

Last week, gunmen attacked an army base in Kaduna state, killing 15 people.

Late last month, terrorists attacked a train in Kaduna, killing eight people and kidnapping dozens of others. Most of the abductees have yet to be freed. In a video released Monday, abductees were seen calling on authorities for help.

Security expert Kabiru Adamu says authorities must take responsibility for failing to protect the public.

"It is very important that we introduce monitoring and evaluation within the security sector and include in this monitoring and evaluation key performance indicators so that persons who let down the ball and allowed these attacks to happen are held accountable and whatever the punishment or penalty for that is meted out on them. We also need to increase the participation of the communities in the security operations," said Adamu.

Last week, Nigerian telecommunications operators complied with a government order to bar phone numbers not registered under the country's national identification scheme, in a bid to track those used by criminals, especially terrorists.