The army in the Democratic Republic of Congo says rebels have shot down a United Nations helicopter in the east of the country.
At least eight people are said to have been on board.
The UN peacekeeping mission said one of its helicopters had disappeared in the Chanzu area, which was attacked by fighters from the M23 group on Sunday night.
The Red Cross says about 6,000 people have fled into neighbouring Uganda where they are being taken to a refugee camp.
DR Congo has accused Rwandan troops of backing the M23, an allegation denied by Kigali.