He grabbed one of the employees at gunpoint and announced his intention to rob the bank, police said.
He then ordered an employee to empty the teller drawers. The suspect took the money from the manager and placed it in a cloth bag and left the bank on foot, police said.
Witnesses described the robber as a white male in his mid 30s, about 5 feet 7 inches tall, 170 pounds with a medium or stocky build. He was described as wearing a white dust mask, black baseball cap, grey long-sleeved shirt, blue jeans, black gloves and black sunglasses.
"Wells Fargo bank is offering a reward of up to $10,000 in exchange for information leading to an arrest," said Chief of Police Phillip Sanchez.
Anyone with any information was asked to contact the Pasadena Police Department at (626) 744-4522.