Police are investigating an aggravated robbery at BP on the Run at St Marys early this morning. At about 3.50am, a man entered the South Road store with part of his face covered, threatened staff with a knife and demanded money. The suspect took off with a small amount of cash. No one was injured during the incident. Patrols with the assistance of dog operations, searched the area but were unable to locate the suspect. The suspect is described as a man of Caucasian appearance, approximately 172cm-178cm tall with a slim build. He was wearing a grey chequered hooded jumper, black trackpants and was carrying a blue backpack.Police will be reviewing CCTV of the incident this morning. – See more at: http://www.sapolicenews.com.au/more-news/23523-armed-hold-up-at-st-marys.html#sthash.myj0Adty.dpuf