The attack on the remote village of Daku in northeast Borno state started on Sunday, and security forces have since confirmed 22 people were killed, the official said, asking not to be named.
The gunmen arrived in a military column and brandished AK-47s, similar to previous Boko Haram attacks, the official said.
The violence is the latest to hit the restive north of Africa's most populous country. In April Boko Haram abducted more than 200 girls from a school in Borno state. The group is looking to carve out a hard-line Islamist state in Nigeria's north. REUTERS