Naseri Paul Biya, governor of the central region of Cameroon, said there could be more casualties.
The stampede happened as crowds struggled to get access to Olembe Stadium in the Cameroon capital of Yaounde to watch the host country play Comoros in a last 16 knockout game in Africa's top soccer tournament.
Officials at the nearby Messassi hospital said they had received at least 40 injured people from the stampede.
“Some of the injured are in desperate condition," said Olinga Prudence, a nurse. “We will have to evacuate them to a specialised hospital.”