A 16-year-old from Mundelein, IL died on Sunday (8/5) after being found unresponsive at Lollapalooza, Chicago Tribune reports. Evan Kitzmiller, who had no identification on him when he arrived, alone, at Northwestern Memorial Hospital, was identified by his mother, Melissa Kitzmiller, who thinks he may have had a seizure. He was pronounced dead at 9 PM.

From the Tribune:

The cause of the teen’s death has yet to be determined. An autopsy conducted by the Cook County medical examiner’s office was inconclusive Monday and the case was marked pending as the office awaited completion of further studies, a spokeswoman said.

The city’s Office of Emergency Management and Communications labeled the incident a “medical emergency’’ and added in a statement: “We are saddened to learn that an individual transported from the event in critical condition last night due to a medical emergency has since passed away.”

Chicago police have launched a death investigation.