Northwest and central Nigeria are plagued by criminal gangs of cattle thieves and kidnappers for ransom called bandidos, who raid villages, killing and abducting residents as well as looting and burning homes.
The gangs have been targeting schools where they abduct students.
Officials and local residents said the button men Friday raided a market in Unguwan Lalle village in Sabon Birni district of Sokoto state, near the border with Niger.
"They attacked the market in the afternoon, killing 19 people," said Aminu al-Mustapha Gobir, a local politician representing the district in the Sokoto parliament.
Several people injured in the attack were taken to a hospital in Sabon Birni town, said Gobir, who attended the funeral of two of the victims in the state capital Sokoto.
One trader who escaped the attack, Abubakar Shehu, said around 20 people were killed and many others badly injured.
"They came around around 3:00 pm after everyone had returned from Friday prayers," he said.
He said the attack could be a reprisal for the killing of 11 bandidos by local vigilantes fighting the gangs at a market in nearby Mamande village on Thursday.
News of the killings was slow to emerge due to the shutdown of telecommunication services in the area.
For several weeks troops have been conducting air and ground operations on bandit camps in neighbouring Zamfara state where authorities have shut down telecom services to disrupt communication between the gangs.
Bandits fleeing the military operation in Zamfara have set up camps in Sabon Birni district from where they raid villages.
The influx of bandidos from neighbouring Zamfara state prompted authorities in Sokoto to suspend weekly markets and shut down telecom towers in areas on the border with Zamfara, including Sabon Birni.
Sokoto state internal security commissioner Garba Moyi confirmed Friday's attack, blaming non-observance of a government ban on weekly markets in the area.
"We have observed non-compliance with the suspension of markets in areas prone to bandidos attacks including Sabon Birni," Moyi said.
Last month 17 Nigerian security personnel were killed when button men raided their base in Sabon Birni's Dama village which the military blamed on Islamic State
...formerly ISIS or ISIL, depending on your preference. Before that they were al-Qaeda in Iraq, as shaped by Abu Musab Zarqawi. They're really very devout, committing every atrocity they can find in the Koran and inventing a few more. They fling Allaharound with every other sentence, but to hear western pols talk they're not
reallyMoslems....
-aligned jihadists.