Human rights groups have called on Nigerian authorities to end sectarian attacks that left at least 35 people dead in northern areas over the weekend.

Amnesty International is among human rights groups condemning the recent attacks in Nigeria and calling for accountability.

In a statement Sunday, the group urged authorities to "immediately and decisively end incessant attacks by gunmen on communities in southern Kaduna." Kaduna is a state in northern Nigeria.

Armed men on Saturday night invaded Unguwan Wakili village in the local district of Zangon Kataf and killed 15 people, most of them women and children.

For many years, the region has suffered from violence involving local farmers and herders, causing thousands of deaths.

Amnesty International said 366 people were killed there between January and July of 2020.

Aminu Hayatu is Amnesty International’s spokesperson.

"Authorities are not living up to the expectation that they bring perpetrators to justice and conduct investigations on those issues, the fact that these kinds of killings have been going on for quite some time. It is quite unacceptable," he said.

Kaduna state police authorities say they're looking into the attack but say initial findings show it could be reprisal for the killing of a herder who was tending to his animals a few days earlier.

Police spokesman Muhammad Jalige did not immediately respond to calls for comment.

Hayatu says authorities have been investigating for too long without taking action.

"The position of the Kaduna state government has been that investigations are going on. [But] we haven't seen a single day that the public has been informed of the findings of the so-called investigations that they claim to be going on by the Kaduna state government and this really calls for worry because it emboldens the perpetrators," he said.

Nigeria has been battling a range of security challenges including insurgency, kidnappings, and communal clashes.

In a separate attack on Saturday, gunmen killed 20 people in northwest Katsina state, according to police.

Isah Gambo, a spokesperson for the Katsina state police, says authorities have restored calm in the affected areas and are keeping watch.

"They came all along from Zamfara state on motorbikes into Katsina state. Although there was stiff resistance from members of the community, police, military and other security agencies were mobilized; even the aircraft went for a rescue mission but unfortunately, they killed 20 members of the community and so many persons were injured also," he said.

Millions of Nigerians went to the polls to elect a new president last month. As outgoing President Muhammadu Buhari's eight-year tenure comes to an end, many hope his successor can do something to rein in the chronic violence and insecurity. (Text, excluding headline: VOA)

•Nigerian soldiers and police officers stand at the entrance of Forestry College in Kaduna state, after a kidnap gang stormed the school