Lambton County OPP are investigating an armed robbery. 
Officers say Tuesday night, am armed masked man went into a convenience store in Petrolia
Witnesses say the man then got into an older model green pickup truck and fled the scene.
OPP officers and the canine unit searched the area but were unable to pick up his trail.
The suspect is described as 6 feet tall with a medium build and short dark hair.
Anyone with any information is asked to contact Lambton OPP.
