A group of unknown assailants killed six people early Saturday at a bar in Sao Paulo, an incident that comes amid a recent wave of violence in Brazil's largest metropolis.

Police said the slayings occurred in the wee hours of Saturday at the bar located in Campo Limpo, a neighborhood in the densely populated south side of the city.

The assailants - whose number was not specified by witnesses - arrived at the bar and without uttering a word fired at a table where nine people were seated, killing six of them.

The other three people suffered gunshot wounds of varying degrees and have been hospitalized.

Police have launched an investigation but it remains unclear if the slayings are related to a surge of violence in Sao Paulo that began in mid-2012 and which federal officials say has been orchestrated by jailed bosses of the First Capital Command, or PCC, the region's dominant criminal organization.

The attacks attributed to the PCC began in May and, according to official figures, have resulted in the deaths of some 100 police officers - many killed while off-duty - in Sao Paulo and neighboring cities.

Two people also have been killed in metropolitan Sao Paulo over the past six months in roughly a score of arson attacks on public buses.

A total of 180 people, according to official figures, were murdered in Sao Paulo in October, a figure that was up 114 percent from the same month in 2011.

The PCC, which controls drug and weapons trafficking in the slums of Sao Paulo and other cities, carried out a series of attacks in Brazil's largest city in 2006.

PCC leaders reportedly run the criminal organization from the prisons of Sao Paulo state, and the gang has become one of Brazil's largest crime groups.

The PCC, also known as the "crime party," first attracted attention in February 2001 when it launched coordinated uprisings in 29 Sao Paulo prisons that left 30 dead and went on for three days.

The current wave of violence was launched by the PCC in retaliation for operations staged by police and death squads against criminals, analysts say. EFE