Three armed and masked men ordered customers and employees to the floor of the credit union at 2763 Fourth St. around 10:15 a.m. and fled with cash in a silver-colored van that was reported stolen in Vallejo, Sgt. Davis Linscomb said.
Witnesses said the suspects abandoned the van and fled in two vehicles. No one was injured in the robbery.
The robbers have a light complexion and were dressed in black hoodie sweatshirts.
One suspect was about 6 feet 2 inches with a thin build and another was 5 feet 8 to 5 feet 9 inches with a stocky build, Linscomb said.
The third suspect was 6 feet and had an average build, Linscomb said.
The Sonoma County Alliance's "Take Back Our Community" has offered a $25,000 reward for the arrest and conviction of the suspects.