Two people were struck by subway trains — one who was killed and the other left clinging to life — in separate incidents within about a half-hour of each other early Friday, police said. 

An unidentified man was on the subway tracks at the Myrtle Avenue station in Bushwick, Brooklyn, around 2:30 a.m. when he was fatally struck by a northbound M train, cops said. 

He was discovered underneath the train and pronounced dead at the scene, authorities said.

Just before 2 a.m., a 45-year-old woman had jumped in front of a northbound No. 2 train at the 116th Street station in Harlem, police in Manhattan said. 

She suffered critical injuries and was taken to Mount Sinai St. Luke’s, authorities said. 

No criminality is suspected in either incident.