A wave of attacks across the Brazilian state of Sao Paulo has left more than 70 people dead, including 35 police officers and prison guards.

Police stations, patrols and off-duty officers have been targeted in the violence, which spread over the weekend.

Unidentified gunmen shot at the Parada de Taipas police station in northern Sao Paulo.

Dozens of prisons have seen riots, which authorities say are being organised by the PCC, a major criminal gang.

Anxious relatives look on as police enter the under-18 Febem da Vila Maria prison, one of many where riots took place.

Some 200 people are being held hostage, including family members who were visiting inmates on Mothering Sunday.

Authorities say the violence began after members of the PCC were moved to maximum-security prisons.

Despite the continuing violence, state authorities have rejected federal help, saying the situation is under control.

Police have set up checkpoints and arrested dozens of people.