Police are looking for a tall white man with a tan jacket and silver-colored gun, according to scanner traffic. The incident happened shortly before 9:30 a.m. at 7340 Westlake Terrace.
Police set up a perimeter around the area including Westfield Montgomery Mall.
It is the second recent bank robbery in the area. A robbery happened on Dec. 20 at the Wells Fargo Bank at 10305 Westlake Dr.