Thirteen people were shot dead over the Labour Day weekend in Chicago, making it the deadliest holiday weekend of one of the worst summers the city has experienced in decades.
The police department said the 13 were among 43 people who were shot over the weekend.
Among them was a pregnant woman who delivered a nearly full-term baby after she was shot in the abdomen.
The woman, who police say was not the intended target, was listed in critical condition. The baby’s condition has not been released.
The holiday weekend killings come amid a dramatic spike in homicides.
Police also said the figures pushed to 488 the total of killings for the year - passing the 481 recorded for all of last year. Nearly 230 homicides occurred in June, July and August.
Last week, the police department said it had officially increased the total of 2015 homicides to 481 from 473.
Spokesman Anthony Guglielmi said the number increased to include victims who were shot in 2015 but died this year, and because in some cases, investigations had been upgraded to homicides.
The number of shootings and homicides over the Labour Day weekend were both higher than the Memorial Day and July 4 weekends and it was the last of the summer holidays before the school year started.
Nine homicides on Monday alone was one more for the entire Labour Day weekend last year.
Police have said the reasons for the rise in homicides are tied to the easy availability of guns and gang violence.
Superintendent Eddie Johnson said that much of the violence is the result of lax gun laws in Illinois that allow those arrested on gun charges to be released from jail far sooner than in other states.
"I’m frustrated... that despite these weekends we still see repeat offenders get back out on the street far too soon," Mr Johnson told reporters.
Referring to reports that Chicago had more homicides than the combined total of the larger cities of New York and Los Angeles in August, he said those cities benefit from tougher gun laws.
"If we had the gun laws they have we’d see violent crime cut in half," he said.
He also reiterated that most of the killings have been concentrated in neighbourhoods on the city’s South and West sides that are plagued with high unemployment and poverty and where gang membership is particularly high.