The as-yet-unidentified 68-year-old man jumped in front of the A train around 6:45 a.m. at 80th Street in Ozone Park, the NYPD said.
The department summoned the bomb squad and shut down the area after responders reported finding the "suspicious device" -- described as a pipe capped at both ends -- in his backpack.
It was later deemed safe.
The man was taken in critical condition to Jamaica Hospital Medical Center in Richmond Hill, they said.
Click here to follow Daily Voice Ridgewood and receive free news updates.