The press secretary of the Salvadoran presidency said, on the social network Twitter, that the stampede at the Cuscatlan stadium, in San Salvador, also caused hundreds of injuries.
A spokesman for the Comandos de Salvamento paramedic corps, Carlos Fuentes, told reporters that about 100 wounded people were transferred to different hospitals and about 500 people were affected by the stampede.
"It was an avalanche of supporters who invaded the gate. Some were still under the metal in the tunnel. Others managed to reach the stands and then the field and suffocated," said Fuentes.
At least two people were transported to the hospital in "critical condition", the Salvadoran National Civil Police wrote on Twitter.
According to initial information from the police, the stampede was started in the 16th minute of a local first division game, between Alianza and CD FAZ, by a group of supporters trying to enter the stadium.