"Survivors of the accident have been transported by foot or by bicycle 12km to the nearest hospital," he said.
Medard Illunga, an official from SNCC, the state railway operator, said the high death toll was due to "clandestine passengers who habitually travel aboard goods carriages unbeknownst to SNCC agents".
The SNCC has set up an inquiry to determine the cause of the accident, the second in Western Kasai province in the space of three weeks.
Joseph Kabila, DR Congo's president, and Antoine Gizenga, the country's prime minister, have elected to send a government delegation to the crash site.
The team would include the ministers of interior, health, humanitarian affairs and transport, Tshilombo said.
The UN peacekeeping force, known by its French acronym MONUC, has sent aid to the accident site, assisting military and civilian authorities.
"[The crash] happened last night around 11 o'clock. This afternoon we sent a helicopter with doctors, nurses, and local authorities. At the moment, they are on the ground there," said Alexandre Essome, a MONUC public information officer in Kananga.
"We suspect there still may be people trapped under the wagons. We need heavy machinery, though, to lift these wagons," Essome said.
MONUC is in Congo to help DR Congo recover from a five-year war that began in 1998.
Up to four million people have been killed by violence or related hunger and disease since the beginning of the conflict.