NEW YORK (Reuters) - A Wal-Mart employee in New York state's Long Island died on Friday when a throng of shoppers surged into the store and physically broke down the doors, a police spokesman said.

The 34-year-old man was at the entrance of the Valley Stream Walmart store when it opened at 5 a.m. local time and was knocked to the ground, the police report said.

The exact cause of death was still to be determined by a medical examiner.

Four shoppers, including a 28-year-old pregnant woman, were also taken to local hospitals for injuries sustained in the incident, police said.

The Friday after America's Thanksgiving holiday is known as Black Friday and marks what is traditionally the busiest retail day of the year, kicking off the Christmas shopping season.

U.S. stores across the country opened in the early hours of Friday to offer discounts to consumers hit by a contracting economy. Hundreds of shoppers waited on line before dawn at some locations to secure deals on holiday gifts.

Representatives at Wal-Mart, the world's largest retailer, were not immediately available for comment.