MECHANICSBURG, Pa.—Authorities in central Pennsylvania are trying to find out why two masked individuals entered a convenience store over the weekend, gunned down the clerk and then apparently left without taking anything.

Police in Cumberland County say the robbery at the Hess Express in Silver Spring Township on Sunday night claimed the life of 55-year-old Linda Ness of Carlisle.

District Attorney David Freed called it "a brazen, brutal crime." He says surveillance video shows Ness appearing to react to what the suspects said but apparently not resisting.

Authorities said the suspects left after less than a minute without taking anything. A customer later found the victim's body behind the counter.

Police are trying to identify the two suspects as well as a third person who entered the store two minutes earlier.