The train was travelling between the country's mains cities, Douala and Yaounde, when it came off the tracks.
The train was overcrowded because a bridge on the road connecting the two cities had collapsed after heavy rain.
Witnesses say carriages were added to accommodate extra passengers. An investigation into the cause of the derailment is under way.
President Paul Biya, who is abroad, wrote on his official Facebook page: "I instructed the government to provide full assistance to the survivors."
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http://www.bbc.com/news/world-africa-37740374