Police investigate deadly stampede

NEW YORK (CNN) - The start of the holiday season has been marred by tragedy after Black Friday erupted into violence around the country.
 
A video from a Long Island Wal-mart shows a worker being trampled to death.
 
Police say the shoppers physically broke down the doors, to get inside the store.

In the process, they knocked down the 34 year-old man, who was then crushed beneath the crowd.  Witnesses say they are appalled by what happened.

Kimberly Gibbs, shopper said, "When they were saying that they had to leave because an employee got killed, people saying, they're yelling, 'I've been on line since yesterday morning'"

Other Wal-Mart employees were also caught in the onslaught while trying to reach the fallen man.
At least four people,  including a woman eight-months pregnant, were injured.