The man, named by media as 54-year-old Idy Diene, died after being shot six times by a 65-year-old who is now in police custody.
Around 300 people took part in a sit-in protest close to where the shooting took place, the Ponte Vespucci (shown on the map below). Diene worked at the bridge selling leather bags and umbrellas to tourists in the city, and was described by friends as "always in a good mood".
Many of the protesters were part of Tuscany's Senegalese community, and were joined by local leftwing activists.
After a small sit-in protest on Mondy afternoon, around 500 demonstrators marched through Florence's streets chanting "no more racism". Later, around 100 of them met with anti-riot police, some of them trying to break through the police cordon, but no clashes or violence were reported.
Italy - #Antifascists are gathering today at 3 pm on the #Vespucci bridge in #Florence, where Idy Diene, 54, from #Senegal, was shot and killed yesterday by an Italian pensioner, to espress their revulsion at #IdyDiene's murder and solidary to his loved ones. #Firenze #6marzo pic.twitter.com/SAuLxdv8al— ANPI Brescia (@AnpiBrescia) March 6, 2018
Florence mayor Dario Nardella expressed his condolences to Diene's family, saying the killing "has hit the whole city", but appealed for calm after some protesters on Monday knocked over rubbish bins and plant pots.
"We understand the pain of the relatives and Senegalese community, but this evening's violent protest in the city centre is absolutely unacceptable," the mayor added, adding that "those responsible for violence" would face justice. He said that public prosecutors had established there was "no racist motive" for the act.
Protesters have disputed this assessment, with one member of Florence's Senegalese community, Pape Diaw, writing on his Facebook page: "I know the murderer very well, he was an ex-colleague of mine. He's not mad at all. He didn't kill randomly, like the newspapers say, he came across many people from his house to the bridge, but chose to kill a black man."
A cartoon by artist Maurio Biani for Italian newspaper Il Manifesto.
Nardella attended a second sit-in at the Vespucci bridge on Monday, but left almost immediately, after being met with insults by some of the protesters. One of them, a local leftwing activist, was reported to police for spitting at the mayor.
The 65-year-old shooter, who left home on Monday with a legally-owned gun, has allegedly told investigators he had at first intended to kill himself on Monday. However, he then decided to shoot "the first person [he] came across", though decided against shooting at a mother and her children who walked past him before he saw Diene.
The perpetrator was later detained by police, who say his statements about the event have been confused.
Diene had a daughter and a partner, who has now been widowed a second time. Her first husband – Diene's cousin – was one of two Senegalese street vendors killed by a far-right activist in 2011, according to Il Corriere Fiorentino.
The murder comes just weeks after a xenophobic shooting attack in the central Italian town of Macerata in February. In that attack, shooter Luca Traini injured six African-born migrants in a drive-by shooting he later said was provoked by news that a Nigerian man had been arrested in connection with the death of a local woman.
Traini's lawyer said he had received an "alarming" number of messages of support for Traini.
The Macerata shooter had earlier stood in local elections as a member of the anti-immigration League party, which became the second biggest party in parliament after Sunday's election. Support for the League rose by 17 points compared to the last election, following a divisive campaign in which immigration was one of the most discussed issues and a top concern of voters.
The party campaigned under the slogans 'Italians First' and 'Stop invasion', with leader Matteo Salvini pledging to deport over half a million migrants he claimed were in the country illegally. In Lombardy, the League's candidate Attilio Fontana was elected with almost 50 percent of the total vote, having caused controversy earlier in the campaign with his calls to "defend our white race".
Salvini has brushed off accusations of racism, saying "racism in Italy is only on the left" and pointing to the party's head of immigration policy, Italy's first black senator and Nigerian migrant Toni Iwobi.