Even for Chicagoans all too accustomed to violence in parts of the city, the weekend stood out. By way of comparison, at least seven people were killed and 32 wounded during the long Memorial Day weekend, the Chicago Tribune reported.

“Our souls are burdened,” Mayor Rahm Emanuel said. “It is unacceptable to happen in any neighbourhood of Chicago. We are a better city.”

Echoing comments that Trump himself has made repeatedly about Chicago, Giuliani blamed Emanuel – Barack Obama’s White House chief of staff – and decades of “one party Democratic rule” in a series of tweets on Sunday and Monday.

The former New York mayor also tweeted his support for Chicago mayoral candidate and former Police Superintendent Garry McCarthy, referring to him as “Jerry” and calling him a “policing genius.”

McCarthy plans to run next February against Emanuel, who fired McCarthy in 2015 after the release of dashcam video showing a white police officer kill a black teenager by shooting him 16 times.

Misspelling Emanuel’s last name, Giuliani tweeted: “He can do a lot better than Mayor Emmanuel who is fiddling while Chicago burns.” Giuliani also falsely claimed that Chicago had “63 murders this weekend.”

The mayor had no immediate comment on Giuliani’s attacks.

Most of the shootings happened in poor neighbourhoods on the West and South Sides where gangs are entrenched, said Police Superintendent Eddie Johnson, standing next to the mayor.

Johnson noted that homicides in the city are down by around 20 per cent from last year. But he said gang members and others arrested on gun charges aren’t dealt with harshly enough.

“It is the same people who are pulling the triggers,” he said. “This is a small subset of individuals who think they can play by their own rules because they continue to get a slap on the wrist when we arrest them.”

Johnson said at the morning news conference there had been no arrests in any of the weekend shootings.

Days before the attacks, some 200 protesters marched through a well-to-do North Side neighbourhood and briefly closed Lake Shore Drive, calling for more resources to stem violence in poor areas.

Tio Hardiman, one of the organisers of last week’s rally, said members of the black community need to take the initiative by mediating truces between gangs.

The violence peaked early Sunday, including one shooting on the South Side that wounded eight people.

Security was increased over the weekend at the outdoor Lollapalooza music festival in downtown Chicago, which drew tens of thousands of young people. But Johnson said the officers were on overtime and weren’t moved from their regular beats in high-crime areas.

City officials say new crime-fighting measures over recent years have helped bring homicide numbers down, including greater reliance on technology that can instantly indicate where gunfire came from. Improved intelligence-gathering has also enabled police to quickly dispatch officers to hotspots where gang violence has just occurred to help thwart revenge attacks.

Chicago ended 2017 with 650 homicides, down from 771 the year before. Though the drop was significant, last year’s total exceeded the combined number of killings in New York and Los Angeles, the two US cities bigger than Chicago.

In a statement, McCarthy called himself a “proud Democrat” and distanced himself from Giuliani’s views and “the misguided, divisive tone and policies of Donald Trump.”

McCarthy said the blame for the bloodshed “lies squarely with Rahm Emanuel’s weak leadership and failed policies,” not with Chicago Democrats as a whole.