At least eight more people have been killed in the Sao Paulo metropolitan area overnight, a public security spokesman said, despite plans by state and federal police to join forces to contain the violence.
State authorities appear unable to contain the murder spree, which experts blamed on a prison drug-gang known as the First Command of the Capital, or "PCC," that is said to be targeting state military police.
Press reports initially spoke of nine deaths in assaults and clashes with police, but a spokesman for the state public security secretariat told the AFP news agency on Thursday that he could only confirm eight.
The latest deaths bring the number of killings, including that of several military police, to at least 55, over the past week.
The PCC has been linked to around 100 murders of police and prison guards across the state this year.
On Tuesday, state and federal authorities agreed to set up a new, joint police agency to spearhead the fight against organised crime.
They also vowed to boost surveillance operations and consider transferring dangerous inmates to maximum-security federal prisons.
Meanwhile, Sao Paulo state governor Geraldo Alckmin reportedly criticised the federal government on Wednesday over the continuing violence.
"The problem is the absence of a federal plan to prevent the influx of arms and drugs at the borders," the daily O Estado de Sao Paulo quoted him as saying.
"If this is not stopped, the problem will continue," the governor added, speaking on the sidelines of a meeting in Brasilia of state governors and Guido Mantega, the finance minister.