The UN's High Commissioner for refugees, Filippo Grandi, said all civilians are in danger demanding an interval for saving lives and delivering aid for those trapped in the war zones.
The Sudanese army bombed the campus of the International University of Africa on Sunday, said Congolese Foreign Minister Christophe Lutundula.
Lutundula has asked the Sudanese government to explain what happened and to return the bodies.
Since the middle of April, the Sudanese armed forces and the Rapid Support Forces (RSF) have fought for control of the country, killing 1,800 people in the process.
Various ceasefires have failed to hold and at the end of May talks between the two sides in Jeddah, Saudi Arabia, fell apart after both sides accused the other of violating the truces.
The UN said that almost 1.4 million people have now been displaced since the fighting started in Mid-April.