He struck at 12:12 p.m. Wednesday at the T-Mobile store in the 200 block of East Delaware Avenue.
Police say a masked man walked into the store, showed a handgun and demanded cash. The clerk complied, and the man fled with an undisclosed amount of money.
Investigators are looking for a white man of average build, approximately 5'8 to 5'10" tall, wearing a black shirt, black pants, black cap, and a black mask concealing his face.
Anyone with additional information about this incident should contact Det. James Skinner at 302-366-7110 ext. 135 or james.skinner@cj.state.de.us .
Anonymous text message tips can be sent by texting 302NPD and the message to TIP411.
Information can also be provided anonymously to Crime Stoppers at 1-800-TIP-3333 or via the internet at www.tipsubmit.com where a reward may be available.
