(CNN) A medical emergency resulted in a young girl being declared dead when her flight landed at Los Angeles International Airport Thursday night, authorities said.

Delta Flight #2423 on its way to Seattle returned to LAX due to a passenger medical issue on board, according to FAA spokesman Ian Gregor.

The passenger was identified as 10-year-old Janice Xu, according to Lt. David Smith of the Los Angeles County Coroner's Office.

An autopsy will be performed in the next day or so, Smith told CNN. No other information will be available until the autopsy is complete.

CNN affiliate KTLA reported that the girl suffered a cardiac arrest on the plane.

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