Police said 90 people were killed last month, a 66% increase over August 2015.

There was a total of 472 shooting victims, an average of more than 15 people per day.

The 90 homicides were the most the city has seen in any month since August 1996, when there also were 90 people killed, according to Chicago Police Department data.

This year's victims included innocent bystanders, including a father paying bills at his kitchen table and the cousin of NBA star Dwyane Wade, who was shot last month while pushing her baby near a school.

However there does not seem to be a clear cause of the rise, although police and mayor Rahm Emanuel frequently point to gang violence and the easy availability of guns.

The city once had some of the nation's strictest gun-control laws, but many are no longer on the books.

Last year, the police department said it confiscated nearly 7,000 illegal guns and added that on Thursday police had taken in 5,900 guns so far this year, an increase of nearly 22% over 2015.

Other people point to a loss of trust between police and the community, a long-standing problem that grew worse after Chicago police released a squad-car video in November showing a white police officer fatally shooting a black teenager 16 times.

The video of Laquan McDonald's death set off weeks of protests.

Most of Chicago's killings have been concentrated in five police districts on the city's South and West sides, where neighbourhoods struggle with gang membership, high unemployment and poverty.

The number of homicides is down or even in six police districts compared with last year, said police.