The museum on Montgomery Street is the site of the first Wells Fargo that opened in 1852. The property features an "impressive display of gold dust and ore from California's Gold Country and a special collection of Gold Rush letters carried by hundreds of express companies."
In view from the glass exterior of the building was a Wells Fargo stagecoach that "carried passengers and gold across the western plains."
Police were alerted about the robbery at 2:26 a.m. this morning. The suspects had assault weapons and held up the security guard, KGO reported.
The men then took off in another vehicle and left the SUV inside the bank, police said.
Authorities are looking for three men in a white Ford Taurus who were last seen heading eastbound across the Bay Bridge, according to KGO's report.
Wells Fargo spokeswoman Diana Rodriguez told ABC News the bank is cooperating with the San Francisco Police Department's investigation.
"We’re disturbed this happened to the Wells Fargo History Museum, but are grateful no team member was harmed," she said in a statement to ABC News. "Additionally, the historic stagecoaches on site were not damaged. Rest assured, the museum will reopen, so it can continue to serve the thousands of visitors and Bay Area residents who visit it each year.”
The San Francisco Police Department did not respond to a request for comment from ABC News.