Thirteen people, including a three-year-old child, have been shot in a park in Chicago.
Chicago police officer Amina Greer said the shootings occurred at about 10.15pm (4.15am Irish time).
The shootings, at a basketball court, appear to be gang-related.
Ms Greer was unable to confirm local media reports that said four of the gunshot victims, including the three-year-old, were listed in critical condition.
Police said that besides the three-year-old, the injured ranged in age from 15 to 41.
Chicago Mayor Rahm Emanuel cancelled two cabinet meetings in Washington to return to his city after being notified of the shooting.
He said: "Senseless and brazen acts of violence have no place in Chicago and betray all that we stand for.
"The perpetrators of this crime will be brought to justice and prosecuted to the full extent of the law."
Chicago has been plagued by gun violence in recent years, with over 500 murders in 2012, according to a report this week by the FBI.
By comparison, New York City, which has a population three times the size of Chicago, recorded 419 murders last year.