Police are seeking the public's help in finding the armed robber who struck at a quiet Chester County shopping center Monday night.

Westtown-East Goshen Regional Police Det. William Cahill said officers responded within one minute to the Walgreens Pharmacy near the intersection of Routes 202 and 926 in Thornbury Township at 9:01 p.m. He said a cashier reported that a man approached the checkout area and requested cigarettes before announcing a robbery and displaying a black semiautomatic pistol.

Cahill said the cashier turned over an undisclosed amount of money and saw the man run toward Route 202.

The bandit is was described as a white male, 5-foot-8 to 5-foot-10 with a beard, wearing a brown leather jacket, a two-tone knit beanie hat with a built-in brim and blue jeans, Cahill said.

Detectives would like to interview two customers who were in the store prior to the robbery, Cahill said. Anyone with information is asked to call police 610-692-5100.

Contact staff writer Kathleen Brady Shea at 610-696-3815 or kbrady@phillynews.com.