A baby boy was born on the sidewalk near a subway station in Downtown Brooklyn on Sunday afternoon, according to a witness and authorities.

His mother began giving birth about 5:40 p.m. on Henry Street between Clark and Pineapple Street, according to an FDNY spokesman.

She left the Clark Street station to look for a cab to the hospital, but had to go into labor on the street when the baby started crowning, a witness said.

Passerbys put cardboard underneath her, and cops and medics helped deliver the baby on a bed sheet.

Spectators applauded when medics took the mother and child into the ambulance, and joked that the newborn should be named Henry.

The two were then taken to Brooklyn Hospital.