Austin police say a man wearing a mask and carrying a hammer robbed a gas station convenience store in the Westlake area Sunday night, the fourth such incident over a five-day span.

A masked man with a hammer robbed a 7-Eleven on Bee Cave Road at Loop 360 (Capital of Texas Highway) around 10:35 p.m. Sunday, Austin police said.

Police have now released an image of what they believe to be the robber’s car, a dark blue Hyundai Sonata with damage to the right rear passenger window.

Police said they believe this is the car of a person who robbed a gas station convenience store on Bee Cave Road.

During the first and second robberies – in which the robber came into the store with a lit Roman candle – the robber wore a yellow Jabbawockeez mask, but during the third and fourth robberies, the person wore a different mask. Details about that mask were not immediately available.

The following Austin convenience stores have also been hit:

A Shell gas station off MoPac Boulevard (Loop 1), just south of Anderson Lane on Sept. 27A 7-Eleven on Airport Boulevard and East 38½ Street on Sept. 29A 7-Eleven on Burnet Road, just north of Research Boulevard, on Sunday

Anyone who knows the person who committed one or more of these crimes is eligible for a reward of up to $1,000 if an anonymous tip is submitted to Crime Stoppers at 512-472-8477 and leads to an arrest.

Anyone with general information to share with police about these robberies can call the Austin police robbery tip line at 512-974-5092.