“This is one of the theories,” said Diego Cardona, secretary for sport for the city of Cali, where the brawl occurred. “But when you have so many people drunk, drugged up and looking for a fight, sometimes it’s hard to find out what really started it.”While violence at sporting events is not unheard of, Saturday’s mayhem involving homemade explosives and knives had the unusual element of fans from the same team – America de Cali – brawling with each other, specifically within its “Red Barons” fan group.The violence flared in the 65th minute of America’s match against Deportivo de Cali. Fighting cascaded from the stands on to the field and then on to the streets surrounding Pascual Guerrero stadium, which has a capacity of about 40,000.In an effort to contain the escalating riot, heavily armored riot police waded into the stands, a move that united the warring fans against the officers, pelting them with rocks and homemade explosives. The police responded by firing tear gas in to the crowd.One fan ran forward and stabbed a police officer three times. Authorities offered on Monday a reward of $5,000 for information leading to his arrest.With the chaos increasing, the referee abandoned the game in the 82nd minute, awarding the victory to Cali, which was leading 1-0.Cardona had no concrete evidence to prove a lover’s quarrel had started the fight, saying it was only one of several explanations police were considering.Cardona said fans identified as taking part in the violence will be banned for 10 games from the stadium’s notorious southern stand, known for its cheap admission price, home to the Red Barons and site of previous confrontations.Tickets for other parts of the stadium cost $25. Entrance to the southern stand costs just $2.50.Colombia’s soccer federation is mulling suspending America del Cali from playing in the stadium for two matches.