Major Gabriel De Brosses, a spokesman for the UN mission in Congo (Monuc), said the mission had sent a rescue team and firefighters to the crash site, which is 5km from the airport.
Joe Bavier, a local journalist, told Al Jazeera that the aircraft crashed into a densely populated slum, and that there were reports that houses had been struck by the aeroplane.
An airport security official who visited the crash site told Reuters that fire crews had experienced difficulty in reaching the burning wreckage.
"There are at least four houses burning, the airplane is burning... There's a lot of smoke and flames, everybody in the houses must be dead," he said.
Papy Kangufu, a resident, told the Associated Press that dense smoke at the crash site was making it difficult to assess the scale of death and injury.
Cargo aeroplanes in Congo are often flown by pilots from former Soviet states, but the aircraft are often poorly maintained and overloaded.
DR Congo's air safety record is one of the world's worst and was called an "embarrassment" by the International Air Transport Association (IATA) last year.
Africa One airlines is on the European Union's list of banned airlines.
All but one of the airlines certified by the DR Congo authorities are banned from the EU.
In 1996, 300 people were killed when an Antonov AN-32 crashed after take-off from Kinshasa's main airport and plowed into a crowded open-air market.