NEW YORK — Police say a worker at a Wal-Mart store in Long Island, New York, has died after being trampled by a throng of unruly shoppers.

Officials say several other people were injured in the incident.

It occurred shortly after the store opened at 5 a.m. on so-called Black Friday, the traditional start of the holiday sales rush in the United States.

Nassau County police say the 34-year-old worker was taken to hospital where he was pronounced dead at about 6 a.m.

The exact cause of death has yet to be determined.

Police also say a 28-year-old pregnant woman was taken to a hospital for observation and three other shoppers suffered minor injuries and were also taken to hospitals.

A police statement said shortly after 5 a.m., a throng of shoppers "physically broke down the doors, knocking (the worker) to the ground."

Officials at Wal-Mart Stores Inc. in Bentonville, Ark., refused to confirm the reports of a stampede, but said a "medical emergency" had caused the company to close the store, which is in Valley Stream on Long Island.

"Local authorities are looking into the situation," said Wal-Mart representative Dan Fogleman.

He said it would be "inappropriate for me to share any additional information" until authorities investigate further.

Shoppers around the United States lined up early outside stores in the annual bargain hunting ritual known as Black Friday.

Many stores open early and stay open late. The Valley Stream Wal-Mart usually opens at 9 a.m.