ST. AUGUSTINE, Fla. -

The St. John County Sheriff's Office is investigating a robbery that happened at the Dollar General Thursday night.

The store is on A1A south near Pope Road. Police say a man approached the 19-year-old female clerk at 9 p.m. and showed a knife in his waistband and demanded money.

Police describe the man as being between 20-30 years old and about 5 feet 8 inches tall with brown hair and eyes. He was wearing a grey hooded sweatshirt with white or green lettering on the front.

Anyone with information concerning this robbery is asked to contact Detective Chris Collins at the St. Johns County Sheriff's Office at 904-209-3981. You can also call Crime Stoppers of Northeast Florida at 1-888-277-TIPS. You can remain anonymous and may be eligible for a cash reward.