United Airlines Boeing 757-224(WL) has crew oxygen leak

A United Boeing 757-200, registration N34137 performing flight UA-510 from Los Angeles,CA to Newark,NJ (USA), was enroute at FL390 about 210nm southwest of Chicago O’Hare,IL (USA) when the crew decided to divert to Chicago reporting a crew oxygen leak and initiating a rapid descent to FL230. The aircraft landed safely on Chicago’s runway 10C about 40 minutes after leaving FL390.
A replacement Boeing 757-200 registration N57111 reached Newark with a delay of 3 hours.
A passenger reported: “we initiated what seemed to be an emergency decent (5000 FPM down) and diverted to KORD where we had to disembark and switch to another 757-200.” The passenger however did not get to know why they diverted to Chicago.
The Aviation Herald