A journalist based in Plateau state said the families of the latest victims had begun receiving ransom demands.
The police have not said anything about the identity of the possible perpetrators.
Kidnapping for ransom by criminal gangs, known locally as bandits, has become common across parts of northern and central Nigeria.
Although the handing over of cash in order to release those being held is illegal, it is thought that this is how many cases are resolved and seen as a way for these gangs to raise money.
The incident in Plateau state is unrelated to the long-running Islamist insurgency in the country’s north-east, where jihadist groups have been battling the state for more than a decade.
The insecurity in Nigeria received renewed international attention in November after US President Donald Trump threatened to send troops to “that now disgraced country, ‘guns-a-blazing'”. He alleged that Christians were being targeted.
Nigeria’s federal government has acknowledged the security problems but has denied that Christians are being singled out.
On Monday, Information Minister Mohammed Idris said that recent tensions with the US over insecurity and alleged persecution of Christians had been “largely resolved”, resulting in stronger relations with Washington.
He added that trained and equipped forest guards will be deployed to secure forests and other remote areas used as hideouts by criminal groups to supplement army operations.
Additional reporting by Abayomi Adisa and BBC Monitoring
