A graphic design firm’s offbeat marketing campaign backfired when a few of the company’s clients mistook test-tube vials they received in the mail for a terrorist attack and called the police.

Shazamm – a Pawtucket-based firm founded in 1999 – was acquired in May by Atrion Networking Corp. of Warwick. (READ MORE) Shazamm’s founder and president, Dana Paul, said the company had been looking for a creative way to publicize the new division’s services to the Atrion client base.