Prime Minister Christian Ntsay said 11 of the injured are in critical condition following the incident at the opening ceremony of the Indian Ocean Island Games in Antananarivo on Friday.
"An unfortunate event happened. There was a stampede at the entrance. There were a lot of injuries. We will observe a few seconds of silence because compatriots have died when they wanted to enter," President Andry Rajoelina told the crowd in the stadium.
Videos shared on social media showed Red Cross workers caring for dozens of injured people next to the athletics track.
After the silence, the ceremony continued with a laser show and fireworks.
The Indian Ocean Island Games were created by the International Olympic Committee (IOC) in 1977, and include athletes from Mauritius, Seychelles, Comoros, Madagascar, Mayotte, Reunion and the Maldives.
At least 15 people were killed in a similar incident at the Mahamasina stadium in 2019.
A police officer is in critical condition after being hit by a train while trying to rescue a distressed man on the tracks.