A smoky basement fire at Macy’s flagship store yesterday was sparked by a discarded cigarette, fire officials said.

A lit cigarette fell through a sidewalk crack and landed in the store’s basement, igniting a blaze that sent smoke wafting through the landmark building yesterday at 3:30 p.m., fire officials said.

Panicked shoppers were forced to flee into Herald Square.

More than 60 firefighters responded to the chaotic scene and put the fire out in about 45 minutes.

An official on the scene said the blaze started in the cellar and spread to a contained area on the first floor.

Fire officials said two customers suffered minor injuries. After the blaze was extinguished, employees and customers were allowed back inside.

(Source: NY Post)