Armed men opened fire on a bus station in southern Sudan Monday, officials said, killing at least four people and prompting authorities to declare a monthlong state of emergency.

Officials in South Kordofan province said the attack in the provincial capital of Kadugli wounded at least four others.

No group immediately claimed responsibility for the attack, which took place as the victims were heading to areas controlled by a rebel group, known as the Sudan People’s Liberation Movement-North, local media reported.

Mousa Gaber Mahmoud, South Kordofan’s acting provincial governor, called the attack “unfortunate,” pledging that local authorities “will spare no effort to regain security and stability” in the province.

He said a state of emergency took effect Monday across the southern province on the border with South Sudan.

The Sudan People’s Liberation Movement-North, led by Abdel Aziz al-Hilu, controls large swaths of the province, including the Nuba mountains. It has been fighting the government in Sudan's capital of Khartoum for decades.

A cease-fire was established between the military and the group following the removal of longtime strongman Omar al-Bashir in April 2019 amid a popular uprising against his three decades of repressive rule.

There were tensions between the two sides after a military coup removed a transitional government in October 2021, plunging the entire country into further chaos.