At least 36 people have been killed in fighting between government and militia forces in the Democratic Republic of Congo, a U.N. spokesman said Thursday.

Among those killed were 10 civilians. At least 3,000 to 4,000 Congolese have taken refuge around a U.N. base in Katanga, said spokesman Eduardo del Buey.

Fighting started on Wednesday in North Kivu province in the country’s eastern region.