The incident unfolded at about 11:35 a.m. Saturday when the suspect walked into the Key Bank branch in the 17300 block of Smokey Point Drive, aimed a handgun at tellers and demanded money.
The suspect then fled the bank on foot with an undisclosed amount of money.
Arlington police officers, Snohomish County sheriff's deputies and Stillaguamish Tribal police arrived within three minutes of the 911 call. A Lynnwood police K-9 police dog also responded and attempted to track down the suspect without success.
The robber is described as a male about 5-feet-8-inches to 5-feet-9-inches in height, with a slender build. He was wearing a light blue or gray zip-up hooded sweatshirt with the hood up, blue jeans with light fading on the front and yellow stitching on the back pockets, and dark or black colored shoes.
The robber also was wearing a black ski mask, scarf or cloth over his face with only the eyes cut out. One witness described the suspect's skin around his eyes as being light in color and the suspect was wearing black gloves and carrying a black backpack.
The suspect's weapon was described as a large frame pistol. The suspect was described as speaking in short, clipped sentences, described as possibly being of an Asian accent.
Surveillance footage from surrounding businesses show a man matching the suspect's description arriving in the area about 30 minutes before the robbery on a bicycle. The suspect was seen riding around to familiarize himself with the area before committing the robbery.
Surveillance video also showed the suspect fleeing the scene toward the north on the bicycle immediately after the robbery.
Anyone with information or who can identify the suspect is asked to contact the Arlington Police Department at (360) 403-3400.