An armed robbery has been reported at Kristina's Variety on Warren Street in Waltham, with a masked man fleeing in a red car, according to Twitter reports.

At around 8:45 p.m., a white male fled the store after showing a knife, according to Twitter user Matthew Carter, @matredsoxfan2. The robber was wearing all black clothes and a mask. It's not clear if anything was taken.

Watertown Police have issued a "be on the lookout" order for the robber, according to Carter. Patch correspondent Stephen Walsh confirmed a robbery had occured. 

Stay tuned to Waltham Patch for updates.