Police in southern Nigeria say seven people were killed late Monday in a clash between officers and protesters calling for the restoration of the former breakaway nation of Biafra.

The police chief of Delta State, Usman Bala Alkali told a reporter for VOA’s Hausa Service that the sides exchanged fire after police tried to stop the marchers from crossing a major bridge spanning the Niger River and connecting the two cities of Asaba and Onitsha.

7 Killed in Nigeria Clashes Between Police, Biafra Protesters

The protesters had no permit for the activities, Alkali said, and some of them were armed.

7 Killed in Nigeria Clashes Between Police, Biafra Protesters

He said a pregnant woman and two police officers were among those killed.

7 Killed in Nigeria Clashes Between Police, Biafra Protesters

Pro-Biafra protesters also marched Tuesday in parts of the five southeastern states that are predominantly Igbo-speaking people.

Biafran separatists declared independence from Nigeria in May 1967 but the movement faltered after a two and a half year war with the Nigerian military.

The Movement for the Actualization of the Sovereign state of Biafra is one of the major groups spearheading a drive to re-establish the country.

Protests have increased since the Nnamdi Kanu, leader of a similar group, the Indigenous People of Biafra, was arrested by Nigerian authorities.