Gunmen killed at least 30 people in an attack in northern Nigeria's Sokoto state, the governor's office said on Monday.

The assault began at a weekly market in Goronyo on Sunday and continued into Monday morning, Sokoto Governor Aminu Waziri Tambuwal said in a statement.

Iliyasu Abba, a local resident and trader, told Reuters that there were 60 bodies at Goronyo General Hospital mortuary, while others sustained injuries while escaping.

"The gunmen stormed the market as it was crowded with shoppers and traders," he said.

The men were "shooting sporadically on us after they surrounded the market firing at every direction killing people."

Abba said the gunmen had at least initially overpowered police who tried to intervene. A police spokesman did not immediately respond to a request for comment.

Gunmen across northwestern Nigeria have killed scores of people and kidnapped hundreds more for ransom over the past year in a security crisis that the government is trying to tackle via communications blackouts, military operations and stepped up policing.

The government ordered shut all telephone and internet services in the whole of Zamfara state in early September, a blackout later extended to parts of Katsina, Sokoto and Kaduna states as military operations intensified.

Tambuwal, in his statement, requested more security forces in the state and the deployment of more resources.