Police say a serial robber handcuffed two employees of the Westbury Babies R Us during an early morning robbery today.

This morning's incident happened at the store located on Corporate Drive. A woman went to the front door around 5 a.m. to let in another female worker, police say. The man entered behind them and pulled out a black handgun.

He put handcuffs on one of the women and forced the other to open a safe. The second worker was then handcuffed as well and forced to lay on top of her co-worker. The man fled with the cash from the safe.

Police say the string of robberies began Aug. 20. Since then, authorities believe the same thief has held up 14 stores across Long Island.

"All the robberies he wears a black type ski mask," says Nassau Detective Lt. Richard Lebrun. "He displays what appears to be a black semiautomatic weapon and he either uses costume handcuffs or zip ties to tie up the victims."

Lebrun also says the man has a pattern for when he strikes.

"We believe he scouts the area to make sure they're either closing or opening," says Lebrun. 

Anyone with information is asked to call Nassau County Crime Stoppers at 1-800-244-TIPS.