Chaos broke out in the stands during the second half of the quarter-final between Alianza and FAS when fans tried to get through a gate and several people were trampled in the chaos.
Nine people are confirmed dead and at least two are critically injured. Dozens of slightly injured fans managed to get onto the football pitch where they received treatment.
“It was like an avalanche of fans storming the gate. Some were still under the metal in the tunnel, others managed to get to the stands and then the pitch and suffocated,” an unidentified volunteer helper told journalists on the scene.
At least nine people died during the commotion at the Monumental stadium.