Abuja: At least 20 Muslim worshippers were shot dead or stabbed to death Sunday by unidentified attackers at a mosque in Nigeria, Xinhua reported.
The attack took place in Dogon Dawa village in Birnin Gwari region of the northern state of Kaduna, police said.
The gunmen went on a house-to-house search, and shot at people indiscriminately. Some of the victims were also stabbed to death, a police officer said.
Yushau Shuaib, spokesperson of the National Emergency Management Agency, said he was not sure if the attack was carried out by a group or "mere armed robbers".
Villagers said the attack was perpetrated by a group of armed robbers who had earlier warned of an assault after their hideouts were revealed to security operatives.
The gunmen, "armed to the teeth seem to be on a revenge mission", a source told Xinhua.
Residents of the area have started fleeing following the attack.
Nigeria`s northern region has been plagued by violence in recent years, with frequent reports of shooting and bomb attacks mostly claimed by the Boko Haram sect.
At least 815 people have been killed by the Boko Haram in Nigeria this year, according to the Human Rights Watch report of October.
Hundreds of attacks by the sect have killed more than 1,500 people since Boko Haram staged an uprising in the northern city of Maiduguri in 2009, the report said.