A Longwood store clerk was forced to the ground at knifepoint during a robbery, police said.

The robbery happened around 5 a.m. Thursday at the Circle K on Ronald Reagan Boulevard near Dog Track Road.

Police said the clerk was alone in the store when a man with a knife entered the store and forced her behind the counter.  The man made the woman open the cash register and told her to get face-down on the ground before he fled.

A search failed to locate the assailant.

Police said the man was wearing a T-shirt over his face, but a detailed description was not released.

The clerk was not injured.

Police said surveillance video captured the robbery, but it has not yet been released.