Sao Paulo was awarded the Copa Sudamericana title on Wednesday when violence on and off the pitch prompted Argentine club Tigre to refuse to play the second half of the second leg of the final.
Tigre officials said their players were attacked in the dressing room area by security officials during the half-time break, following confrontations on the pitch at the end of the first half.
Tigre coach Nestor Gorosito came to the field briefly during the half and told reporters "they pulled two revolvers," he said referring to unspecified security officials.
"We're not going to play anymore."
Referee Enrique Osses of Chile awarded the victory to Sao Paulo after waiting about 30 minutes for Tigre to retake the field.
The two teams scuffled going off the pitch after the first half, and Argentine television showed what appeared to be blood-spattered walls.