The stampede at Tata Raphael Stadium in Kinshasa happened toward the end of a match Sunday between AS Vita Club and TP Mazembe.
At least 21 others were hurt, said Gov. Andre Kimbuta, who has set up a commission to investigate the incident.
On Monday, Congolese government spokesman Lambert Mende defended the actions of the security officers.
“It is false to say that the violence was started by the tear gas, which was used to protect people being threatened by elements in the stands who were acting like militiamen,” he said.
Three of the injured remained in the hospital, Mende said.
Witnesses said angry fans threw objects onto the field, including rocks, in the final minutes of the match on the last day of the league season. The home team, AS Vita, was losing 1-0.
Kanga Yves said that the crowds were trampled as they tried to flee the tear gas.
The stampede caused a recently restored wall and gate to collapse, the Confederation of African Football said in a statement Monday. The continental body has asked Congolese soccer authorities for a report.
FIFA President Sepp Blatter said on Twitter he was waiting for more information from Congo after the “tragic reports.”
“My thoughts are with all those who saw loved ones go to a game, not to return,” Blatter wrote.
Fights have previously erupted when Kinshasa-based AS Vita played Lubumbashi-based TP Mazembe, a four-time African club champion.
Sanctions had been imposed last season on the teams after a match in Lubumbashi, U.N.-backed Radio Okapi reported.
More than 20 people were killed on April 25 in the town of Kikwit in southwest Congo when generators failed during a festival honoring a popular singer, plunging the stadium into darkness and causing a stampede.
Sunday’s Kinshasa stadium stampede also came days after Ghana marked the anniversary of Africa’s worst football disaster. Over 120 people were killed on May 9, 2001 when police fired tear gas at a stadium in the Ghanaian capital Accra because of crowd trouble at a game, also causing a stampede in the stands.
Most recently, more than 70 people died in a riot at a football game in the Egyptian city of Port Said in February 2012. The riot was linked to political violence in Egypt following the overthrow of Hosni Mubarak as president.