At least four people were killed and seven others injured Thursday in two related shooting incidents in Brazil's largest city Sao Paulo, official sources said.

The incidents occurred just past daybreak Thursday and police suspect the same assailants of being behind both attacks, since eyewitnesses in the Sao Paulo districts of Carapicuiba and Osasco, where the shootings occurred, reported seeing the same car with two people aboard.

In Carapicuiba, police said a hooded man got out of a car and opened fire at a bar, instantly killing a 19-year-old man who was with a group of four people, and a second victim from that shooting died later in the hospital, and the other three were injured.

About a kilometre from the bar, a man sitting in a plaza was shot dead, by presumably the same attacker, while another person nearby was wounded.

In the district of Osasco, four people were shot, one of them fatally.

Sao Paulo and its metropolitan area saw a surge in violence in the second half of 2012, registering 1,400 people murdered, 34 percent more than in 2011.

Authorities say last year's wave of violence was due to a war against the police force by drug traffickers, who killed more than 100 officers.

Between January and February of this year, 200 people were murdered in Sao Paulo, 14.3 percent more than the same period last year.

In Sao Paulo state, 846 murders were registered in the first two months of 2013, 15.5 percent more than the 732 murders registered over the same period in 2012.