"Only when the inquiry put in place by the prime minister, head of government, and by the railway manager, only when these inquiries are completed, then we will give you the reason why this accident took place and the number of casualties," he said.
Officials said the train was carrying more than 1,000 passengers.
A day earlier, a train carrying gas and petrol derailed and burst into flames, killing at least one person.
The government has set up inquiries into the two accidents and vowed to pay the medical costs for the injured.
French industrial giant Bollore has a contract to operate Cameroon's national railway until 2020 and has plans for a $300m upgrade for the country's railway and rolling stock.