Chicago Fire Department spokesman Larry Langford said firefighters were called to the airport about 7:45 a.m. local time (11:45 p.m. Thursday AEST) because a person was trapped in a baggage-carrying machine. He said they discovered the woman in a baggage compartment caught in a conveyor belt system.

Police said she was 57 years old but did not release her name.

The baggage compartment was not open to the public, Langford said, and it was unclear how she got in. Scott Allen, a spokesman for the U.S. Department of Labor, said an Occupational Safety and Health Administration official visited the scene and learned the woman was not an airport employee.

The fire department turned the scene over to police investigators, and Langford could not provide further details. The Chicago Police Department’s communications office said in an email to The Associated Press that the woman was found unconscious and pronounced dead at the scene. Investigators have launched an investigation, the office said.

The police dispatch initially said the woman was discovered at 2:27 a.m., leading to confusion about why firefighters and paramedics did not arrive for more than five hours. After asking police exactly when, Langford said he was told surveillance footage showed the woman going into the luggage compartment at 2:27 a.m.

The communications department issued a second statement Thursday afternoon, saying surveillance video showed the woman entering the room at 2:27 a.m. She was actually discovered at 7:30 a.m., prompting a 911 call.

The footage only shows her walking and not what happened to her.

Police spokesman Nathaniel Blackman clarified in a telephone interview with the Associated Press that no one had watched the surveillance cameras in real time and that investigators only reviewed the footage after the woman’s body was discovered.