Westbrook police provided this image from a video of Thursday night’s robbery at the Big Apple store on Main Street.

Westbrook police are searching for a man who assaulted a clerk at a convenience store and threatened him with a knife during a robbery Thursday afternoon.

The male suspect, whose image was caught on surveillance cameras, assaulted the clerk at the Big Apple store on Main Street around 4 p.m., Westbrook police said in a Facebook post.

Police said the robber, who remained at large late Thursday evening, took off on foot with a tip jar containing cash.

Though the images are grainy, the robber appears to be wearing a baseball cap and a camouflage jacket.

Anyone with information should contact Westbrook police at 854-0644 or ask to speak with Officer Jacqueline Lorenzen. Anonymous tips can be left at 591-8117.