The shootings took place days after a Nigerian man was arrested in connection with the murder of an Italian woman in Macerata.
Police tweeted a picture of the alleged gunman, who was wearing an Italian flag and reportedly made a fascist salute when he was arrested.
The mayor said the victims were five men and one woman and at least one person was in serious condition.
Hospital officials say one of the six Africans wounded by a far-right Italian gunman has been treated for their injuries and released.
The mayor of city, Romano Carancini, had asked population to calm down until police operation ended and y remained closed in houses and ir work because of danger situation.
Residents had been told to stay inside during the shooting and public transport was halted. Shortly afterwards, police said one man had been arrested. A 29-year-old Nigerian man was detained as a suspect, prompting parties like the Northern League to decry the crime and push their nationalist agenda.
Luca Traini, 28, suspected by the Police of opening fire on African migrants, is seen in Macerata, Italy, February 3, 2018.
"Everything that happened between the death of Pamela and today was fanning the flames of hate between people", said Carancini, of the center-left Democratic Party, in an interview.
After the attack, Italian Prime Minister Paolo Gentiloni called on political leaders on all sides to stop a "cycle of violence".
Her body was found on Wednesday and a preliminary post-mortem could not immediately identify the cause of death.
The news agency ANSA said two of the injured were black, and that witnesses reported that the vehicle was seen in the area where the woman's body was found.
Salvini's League, which dropped the "northern" from its name in a bid for a national following, has joined a centre-right coalition with Silvio Berlusconi's Forza Italia and Giorgia Meloni's much smaller Brothers of Italy. "Whether or not you agree with the government's immigration policies, we must not stoke violence", he said.