Tyshaun McClurge,17, was shot to death Saturday night at a friend's house, and authorities believe he might have accidentally shot himself.
Calumet City police investigators updated the case Monday morning as they awaited the results of an autopsy being performed the same day.
"This seems to be, on the onset, a very tragic accident," said Calumet City Police Asst. Chief Dante Zorzi.
Authorities were being cautious not to label the shooting death as an accident prematurely.
"We want to be sure that all of our bases are covered and all of the witnesses are interviewed, and we need the autopsy and the evidence to support some of the things that are being told to us at this time by witnesses," said Zorzi.
Preliminary reports appear to indicate that a bullet was inadvertently left in the chamber of the gun, even though the clip was removed.
Police say it is unclear where the gun came from.
McClurge is the second Calumet City teenager to die from gunfire in the span of a week.
"Unfortunately, it's happening across the country. [It's] something that needs to be addressed, as far as how these kids are getting guns in their hands," Zorzi said.
Pamela McClurge, Tyshaun's aunt, told ABC7 the gun did not belong to her nephew, and she could not imagine where it came from.