Thieves in ski masks smashed a stolen sport utility vehicle into the site of the original Wells Fargo Bank in San Francisco’s Financial District early Tuesday and held a security guard. The crash-and-grab heist — the latest of a series of similar incidents in San Francisco — happened about 2:30 a.m. at the bank’s museum at 420 Montgomery St.

The intruders rammed the GMC Suburban through the museum’s glass revolving doors, police said. A security guard investigating the crash was held at gunpoint by the assailants, who then smashed into display cases and made off with historic nuggets and gold ore, police said.

The robbers, wearing ski masks, hoodies and jeans, abandoned the SUV inside and fled in a four-door car, possibly a Ford Taurus. Police said at least one suspect was armed with a handgun.

It was unclear how much the bandits made off with in the scheme, but one gold nugget was visible at the crime scene early Tuesday morning. According the the museum’s website, “an impressive display of gold dust and ore from California’s Gold Country,” are on exhibit in the building.

The museum is located on the site where Wells Fargo Bank opened in 1852. Besides the gold, the museum features other artifacts, including a historic red and gold stagecoach — the emblem of the nation’s fourth largest bank. The stagecoach was not damaged in the robbery.

“We’re disturbed this happened to the Wells Fargo History Museum, but are grateful no team member was harmed,” a company spokesman, Ruben Pulido, said in a statement.

Officials said the museum will reopen once the damage is cleared.

People walking past the ravaged entry early Tuesday stepped over piles of broken glass, many snapping pictures while staring quizzically at the wreckage of the audacious crime.