Doctors Without Borders says the death toll is nearing 3,000.
The peacekeepers have been accused of detaining, abusing, torturing and killing civilians.
The fighting started on Thursday after anti-Balaka fighters looted Seleka food reserves, residents said.
The EU drew up plans to send 800 - 1,000 soldiers to CAR to join 6,000 African and 2,000 French troops.
Mass killings have continued despite the presence of 2,000 French and 6,000 African Union peacekeepers.
The Red Cross recovered 13 bodies from the streets of Bangui on Monday and treated eight wounded.