A boozed-up elderly man had his leg severed by a Brooklyn subway train after tumbling on the tracks this evening, police said.

The 66-year-old man, who was not immediately identified, was “highly intoxicated” when he fell onto the northbound D-line tracks at the Bay 50th Street station at Stillwell Avenue in Gravesend at 7:37 p.m., authorities said.

He was rushed to Lutheran Hospital in critical condition with his left leg cut off below the knee and right leg crushed.