A least twenty people were killed and seven injured in a wave of Thursday/Friday overnight shootings in Brazil's biggest city, Sao Paulo, some of them gunned down in cold blood as they sat in a bar.Alexandre de Moraes, head of the Sao Paulo state security department, announced the death tally -- originally placed at 20 -- Friday after media reports of a deliberate massacre in the suburbs, possibly by rogue police.
The murders were shocking even in a country used to runaway violence.
What I can say for sure is that it's the biggest killing this year, de Moraes said.
O'Globo News television broadcast security camera footage of one attack, showing a group of masked assailants entering a bar, ordering clients to raise their hands in the air, then shooting them.
Folha de Sao Paulo newspaper quoted witnesses saying that the killers stopped their targets and questioned them about their criminal records then executed them.
Earlier, a spokesman for the security forces had described the wave of killings late Thursday as unusual. The shootings occurred in the Osasco and Barueri areas, reportedly all in a period of about two and a half hours.
The mayor of Osasco, Jorge Lapas, said video footage supports a theory that the killings could have been reprisals for the earlier death of a police officer.
We want to take measures so that the situation does not worsen over the coming days, he said.
De Moraes said investigators had analyzed spent cartridges to establish whether the shooters were from a single group and had determined there were in fact two groups.
He said a police link had not been ruled out. One of the theories being considered was a possible connection to two robberies, one of which took place last Friday when a military police officer was murdered and another where a civil guard died.
Both those killings took place in the neighborhoods where Thursday's mass shootings occurred. Investigators are also looking into possible drug-trade connections. De Moraes said he was sure that the police will solve it quickly.