A Palmeiras fan was declared brain dead on Tuesday, the second casualty from a confrontation involving nearly 500 people from rival groups last weekend.
The Sao Camilo hospital said the 19-year-old fan remains on a ventilator but will not recover after receiving head injuries in the fighting on Sunday. His name was not immediately released by the hospital.
On Sunday, 21-year-old Palmeiras supporter Andre Alves died after being shot in the head in the confrontation. Two other fans remain hospitalized, a 17-year-old with head injuries and a 23-year-old who was shot in the hip and needed surgery.
The announcement that the fan was brain dead came as authorities decided to close the headquarters of the rival fan groups involved in the fighting — Palmeiras' Mancha Verde and Corinthians' Gavioes da Fiel. The Sao Paulo state soccer federation indefinitely banned them on Monday from entering stadiums.
Authorities seized computers and other material that could bring more information about those involved in the fight, and detained several members suspected of participating in the confrontation. Iron bars and other possible weapons used in the brawl were also seized.
Police said one of Alves' brother, a vice president at the Mancha Verde, was shot in the leg during another fight last year.
The confrontation on Sunday raised concerns about escalating fan violence in Brazil, and authorities said they will have to take action to keep the fighting from spreading with the country staging the 2014 World Cup. Corinthians' stadium will host the World Cup opener in 2014.
"We are against this type of violence because everybody loses," said former Palmeiras player and current club director Cesar Sampaio, who attended Alves' funeral on Monday. "We have to take a stance to try to put an end to this right now."
There hadn't been a death linked to fan violence in Brazil since early last year, when a Corinthians supporter was killed after reportedly being ambushed by Palmeiras fans. Police believe the fight Sunday came in retaliation for that death. Palmeiras supporters are already using social media networks to say they will avenge this weekend's killing.
Police were investigating reports that Sunday's fight was set up on the Internet. The Mancha Verde released a note saying the group was ambushed by the Corinthians supporters, but the Gavioes da Fiel denied the allegations.
The fans used iron bars, pieces of wood and rocks in the confrontation that lasted several minutes until riot police arrived to intervene. It happened several hours before the match between Corinthians and Palmeiras, several kilometers from the stadium.
There had been few incidents involving fan groups in the past few years, but several have been reported in recent months, including some between Corinthians and Palmeiras fans.
About a week ago, a 28-year-old fan of small club Guarani died from head injuries after fighting with Ponte Preta supporters in the city of Campinas, about 60 miles from Sao Paulo. The death prompted authorities to ban the teams' fan groups from stadiums.
Other South American nations have had to deal with fan violence. One man was killed and dozens were injured in two separate incidents in Colombia this month.
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