After the assault in the central town of Macerata, the suspect got out of his car and made a fascist salute with a tricolour Italian flag draped over his shoulders, Italian media reported.
Six people including "persons of colour" were injured, four of them seriously, media reported.
Police confirmed in a tweet that "the wounded persons were of foreign nationality", adding that the "presumed author of the attack is Italian".
Television footage showed the suspect, sporting a shaved head, being arrested at the town's war memorial.
Police also posted a photo of the capture.
Media said police had seized a gun in the man's vehicle.
Reports named the suspect as Luca Traini, a member of the far-right Northern League party, who had run in local elections last year.
The attack comes a day after a Nigerian asylum-seeker was arrested in Macerata over the gruesome killing of an 18-year-old Italian woman whose dismembered body was discovered in suitcases earlier this week.
However, no official link has been made between the two incidents.
Italians head to the polls in national elections in March, with immigration shaping up to be a key issue.
The Northern League is part of a populist coalition tipped to do well.
According to opinion polls, the alliance between ex-prime minister Silvio Berlusconi's centre-right Forza Italia (Go Italy), the post-fascist Fratelli d'Italia (Italian Brothers) and the Northern League leads with more than 35 percent ahead of the March 4 vote.
People gather where witnesses say a shooter was arrested in Macerata.
Italian police have arrested a far-right supporter suspected of wounding several foreigners in a drive-by shooting on Saturday, in what local media called a racially motivated attack.
