At least 11 people died of gunshot wounds in several shootings overnight in different parts of Greater Sao Paulo, which has seen a recent uptick in violence, police said.

Five people were killed in armed clashes on the east side of Sao Paulo, hard hit by violent crime in recent days, while the other six were slain in various municipalities of the metropolitan area.

Most of the attacks were carried out by armed men riding on motorcycles, the official Agencia Estado news agency said.

A Sao Paulo state Public Safety Secretariat spokesperson consulted by Efe confirmed the deaths of six people and added that a police officer had been shot, though without specifying his condition.

On Friday, authorities said seven people had been killed in similar overnight attacks beginning Thursday evening in Sao Paulo state, where 86 Military Police officers have been killed thus far this year.

The resurgence of violence has sparked fears among the population and led to talk of an alleged curfew being imposed in Osasco, a city of Greater Sao Paulo, although security forces have denied the rumor.

Sao Paulo city witnessed 135 homicides last month, an increase of 27 percent from August and a 96 percent jump compared with September 2011.

Authorities are investigating whether the recent murders of police were the work of the First Capital Command, or PCC, Sao Paulo's largest criminal outfit.

The PCC is involved in drug and arms trafficking and truck hijackings. EFE